編輯：關於Android編程
在項目中有一個小功能需要實現，就是對多行文本進行排版布局，每一行的內容又分為兩部分，左邊為標題，右邊為描述，左邊內容長度不確定，右邊的內容需要對齊，如有換行也需要對齊右邊的文本。
效果圖如下圖所示：
vcTayN231rPJwcvBvbK/t9ajrNfzsd+1xNHVyavT69PSsd+yu9K71sKjrNPSsd+1xMPoyvbOxLC4zbPSu7bUxuuhozwvcD4NCjxoMyBpZD0="實現方案">實現方案
以上功能，由於輸入內容輸入行數不確定，並且左邊的文案長度也不確定，因此不能直接在布局中實現，基於此這裡主要實現了以下6種方式
采用自定義控件的方式，繼承TextView，重新onDraw函數，實現如下：
/**
* 計算出左邊最長的顯示字符串maxLeftWidth，之後draw每一行字符，右邊的描述從maxLeftWidth開始draw
* 當一行顯示不完全時，折行並且空出maxLeftWidth的空格長度
*/
public class TypographyView1 extends TextView {
private Paint leftPaint = new Paint();
private Paint rightPaint = new Paint();
private int fullWidth;
private float textSize;
private JSONArray array;
private int middlePadding = 0;
float maxLeftWidth = 0;
int itemSize = 0;
public TypographyView1(Context context) {
super(context);
init();
}
public TypographyView1(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TypographyView1(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
leftPaint.setAntiAlias(true);
leftPaint.setTextSize(textSize);
leftPaint.setColor(getResources().getColor(R.color.color_black_999999));
rightPaint.setAntiAlias(true);
rightPaint.setTextSize(textSize);
rightPaint.setColor(getResources().getColor(R.color.color_black));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
fullWidth = getWidth();// 整個textView的寬度
}
public void setText(JSONArray array) {
this.array = array;
if (array != null) {
try {
int size = itemSize = array.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) array.get(i);
String key = o.getString(0);
String value = o.getString(1);
if (TextUtils.isEmpty(key) || TextUtils.isEmpty(value)) {
itemSize--;
continue;
}
float curWidth = leftPaint.measureText(key);
if (curWidth > maxLeftWidth) {
maxLeftWidth = curWidth;
}
}
maxLeftWidth = maxLeftWidth + middlePadding;
invalidate();
} catch (Exception e) {
}
}
}
boolean setHeight = false;
@Override
protected void onDraw(Canvas canvas) {
if (array == null) {
return;
}
int lineCount = 0;
try {
JSONArray item;
float offsetY;
for (int i = 0; i < itemSize; ++i) {
item = (JSONArray) array.get(i);
offsetY = (lineCount + 1) * textSize;
canvas.drawText(item.getString(0), 0, offsetY, leftPaint);
String value = item.getString(1);
float valueWidth = rightPaint.measureText(value);
if (valueWidth > fullWidth - maxLeftWidth) {// 一行顯示不完
char[] textCharArray = value.toCharArray();
float charWidth;
float drawWidth = maxLeftWidth;
for (int j = 0; j < textCharArray.length; j++) {
charWidth = rightPaint.measureText(textCharArray, j, 1);
if (fullWidth - drawWidth < charWidth) {
lineCount++;
drawWidth = maxLeftWidth;
offsetY += textSize;
}
canvas.drawText(textCharArray, j, 1, drawWidth, offsetY, rightPaint);
drawWidth += charWidth;
}
} else {
canvas.drawText(value, maxLeftWidth, offsetY, rightPaint);
}
lineCount += 2;
}
if (!setHeight) {
setHeight((lineCount + 1) * (int) textSize);
setHeight = true;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
添加了setText(JSONArray array)作為數據輸入，並且在這裡面測量了左邊title的最大寬度，之後調用invalidate觸發重繪，在onSizeChanged獲取整個控件的寬度，重繪會調用onDraw函數，這裡不需要調用super函數，TextView的onDraw函數做了非常多的操作，解析傳入的數據，分別一行一行調用canvas來進行drawText操作，當繪制描述時，先計算寬度，如果超過剩余控件說明需要換行，最後調用setHeight設置高度，這個加一個判斷條件，因為會觸發requestLayout()進行重新布局和invalidate()進行重繪，如果不加判斷會一直重繪。
方式2與方式1差不多，不同為所有計算都在onDraw函數中：
/**
* 該方式與方式1很類似，只是所有的計算都放在了onDraw方法中。
*/
public class TypographyView2 extends TextView {
private Paint paint1 = new Paint();
private Paint paint2 = new Paint();
private int middlePadding = 0;
int width;
private float textSize;
private JSONArray array;
public TypographyView2(Context context) {
super(context);
init();
}
public TypographyView2(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TypographyView2(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
paint1.setAntiAlias(true);
paint1.setTextSize(textSize);
paint1.setColor(getResources().getColor(R.color.color_black_999999));
paint2.setAntiAlias(true);
paint2.setTextSize(textSize);
paint2.setColor(getResources().getColor(R.color.color_black));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = getWidth();// 整個textView的寬度
}
public void setText(JSONArray array) {
this.array = array;
if (array != null) {
invalidate();
}
}
boolean setHeight = false;
@Override
protected void onDraw(Canvas canvas) {
// super.onDraw(canvas);
int lineCount = 0;
int size = array.length();
float maxLeftWidth = 0;
float drawWidth = 0;
try {
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) array.get(i);
String key = o.getString(0);
float v = paint1.measureText(key);
if (v > maxLeftWidth) {
maxLeftWidth = v;
}
}
maxLeftWidth = maxLeftWidth + middlePadding;
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) array.get(i);
String key = o.getString(0);
canvas.drawText(key, 0, (lineCount + 1) * textSize, paint1);
String value = o.getString(1);
char[] textCharArray = value.toCharArray();
float charWidth;
drawWidth = maxLeftWidth;
for (int j = 0; j < textCharArray.length; j++) {
charWidth = paint1.measureText(textCharArray, j, 1);
if (width - drawWidth < charWidth) {
lineCount++;
drawWidth = maxLeftWidth;
}
canvas.drawText(textCharArray, j, 1, drawWidth, (lineCount + 1) * textSize, paint2);
drawWidth += charWidth;
}
lineCount += 2;
}
if (!setHeight) {
setHeight((lineCount + 1) * (int) textSize + 5);
setHeight = true;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
該方案的實現是不太好的，方案1也是在此基礎上進行調整的，在這裡放出來只是為了說明，所有的計算不要全部放在onDraw裡面，因為該方法可能會反復調用多次，這樣就降低了性能。
將數據源拼接成SpannableString，重寫onDraw函數，根據內容draw每一個字符：
/**
* 該方法，是需要顯示的內容先拼接成SpannableString，在onDraw方法中獲取所有的char字符，一個一個比較
* 當為分號是，表示為key與value的分隔符。
*/
public class TypographyView3 extends TextView {
private Paint leftPaint = new Paint();
private Paint rightPaint = new Paint();
int width;
private String text;
private float textSize;
float maxLeftWidth = 0;
private int middlePadding = 0;
public TypographyView3(Context context) {
super(context);
init();
}
public TypographyView3(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TypographyView3(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
leftPaint.setAntiAlias(true);
leftPaint.setTextSize(textSize);
leftPaint.setColor(getResources().getColor(R.color.color_black_999999));
rightPaint.setAntiAlias(true);
rightPaint.setTextSize(textSize);
rightPaint.setColor(getResources().getColor(R.color.color_black));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = getWidth();// 整個textView的寬度
}
public void setText(JSONArray data) {
if (data == null) {
return;
}
try {
int size = data.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) data.get(i);
String key = o.getString(0);
float v = leftPaint.measureText(key);
if (v > maxLeftWidth) {
maxLeftWidth = v;
}
}
maxLeftWidth += middlePadding;
SpannableStringBuilder ssb = new SpannableStringBuilder();
for (int i = 0; i < size; ++i) {
addItem((JSONArray) data.get(i), ssb, i != 0);
}
setText(ssb, BufferType.SPANNABLE);
} catch (Exception e) {
}
}
private void addItem(JSONArray item, SpannableStringBuilder ssb, boolean breakLine) {
try {
if (item == null || item.length() == 0) {
return;
}
String key = item.getString(0);
String value = (item.length() >= 2) ? item.getString(1) : "";
if (TextUtils.isEmpty(key) && TextUtils.isEmpty(value)) {
return;
}
if (breakLine) {// 換行
ssb.append("\r\n");
ssb.append("\r\n");
}
SpannableString span = new SpannableString(key);
// span.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.colorAccent)), 0, key
// .length(),
// Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
ssb.append(span);
ssb.append(value);
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
protected void onDraw(Canvas canvas) {
// super.onDraw(canvas);
int lineCount = 0;
text = this.getText().toString();
if (text == null)
return;
char[] textCharArray = text.toCharArray();
// 已繪的寬度
float drawWidth = 0;
float charWidth;
Paint paint = leftPaint;
for (int i = 0; i < textCharArray.length; i++) {
charWidth = leftPaint.measureText(textCharArray, i, 1);
if (textCharArray[i] == '\n') {
lineCount++;
drawWidth = 0;
paint = leftPaint;
continue;
}
if (width - drawWidth < charWidth) {
lineCount++;
drawWidth = maxLeftWidth;
}
if (i > 1 && textCharArray[i - 1] == ':') {
drawWidth = maxLeftWidth;
paint = rightPaint;
}
canvas.drawText(textCharArray, i, 1, drawWidth, (lineCount + 1) * textSize, paint);
drawWidth += charWidth;
}
//may be need set height
//setHeight((lineCount + 1) * (int) textSize + 5);
}
}
這裡先計算左邊title的最大寬度，同時將所有的數據拼接成一個SpannableStringBuilder，調用setText函數會觸發重繪，在onDraw函數中進行處理，由於未重新super函數，因此SpannableString的setSpan函數失效，該方案主要根據分隔符來進行分割，因此分隔符需要唯一。
采用GridLayout方式實現，但是原始控件有展示問題，因此對此進行了修改：
public class Typography4Activity extends BaseActivity {
public static void start(Context context) {
Intent intent = new Intent();
intent.setClass(context, Typography4Activity.class);
context.startActivity(intent);
}
private LinearLayout root;
private Paint leftPaint = new Paint();
private float textSize;
private float maxLeftWidth;
private int middlePadding = 0;
private float maxRightWidth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
root = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.activity_typography4, null);
setContentView(root);
initPaint();
findViews();
loadData();
}
private void initPaint() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
leftPaint.setAntiAlias(true);
leftPaint.setTextSize(textSize);
leftPaint.setColor(getResources().getColor(R.color.color_black_999999));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
private void findViews() {
}
private void loadData() {
addGridLayout(DataSource.getArray());
TextView view = new TextView(this);
view.setText("修改後的實現");
view.setGravity(Gravity.CENTER);
view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 160));
root.addView(view);
addModifyGridLayout(DataSource.getArray());
}
private void addGridLayout(JSONArray data) {
try {
GridLayout layout = createGridLayout();
int size = data.length();
for (int i = 0; i < size; ++i) {
JSONArray item = (JSONArray) data.get(i);
String key = item.getString(0);
String value = (item.length() >= 2) ? item.getString(1) : "";
GridLayout.Spec row = GridLayout.spec(i);
GridLayout.Spec col1 = GridLayout.spec(0);
GridLayout.Spec col2 = GridLayout.spec(1);
GridLayout.LayoutParams params = new GridLayout.LayoutParams(row, col1);
TextView title = getLeftTextView(key);
layout.addView(title, params);
params = new GridLayout.LayoutParams(row, col2);
TextView desc = getRightTextView(value);
layout.addView(desc, params);
}
root.addView(layout);
} catch (Exception e) {
}
}
@NonNull
private TextView getRightTextView(String value) {
TextView desc = new TextView(this);
desc.setTextSize(13);
desc.setTextColor(getResources().getColor(R.color.black));
desc.setText(value);
return desc;
}
@NonNull
private TextView getLeftTextView(String key) {
TextView title = new TextView(this);
title.setText(key);
title.setPadding(0, middlePadding, middlePadding, 0);
title.setTextColor(getResources().getColor(R.color.color_black_999999));
title.setTextSize(13);
return title;
}
private void addModifyGridLayout(JSONArray data) {
try {
calculateLeftMaxWidth(data);
GridLayout layout = createGridLayout();
int size = data.length();
for (int i = 0; i < size; ++i) {
JSONArray item = (JSONArray) data.get(i);
GridLayout.Spec row = GridLayout.spec(i);
String key = item.getString(0);
GridLayout.Spec col1 = GridLayout.spec(0);
GridLayout.LayoutParams params = new GridLayout.LayoutParams(row, col1);
TextView title = getLeftTextView(key);
layout.addView(title, params);
String value = (item.length() >= 2) ? item.getString(1) : "";
GridLayout.Spec col2 = GridLayout.spec(1);
params = new GridLayout.LayoutParams(row, col2);
TextView desc = getRightTextView(value);
params.width = (int) maxRightWidth;
params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
layout.addView(desc, params);
}
root.addView(layout);
} catch (Exception e) {
}
}
private void calculateLeftMaxWidth(JSONArray data) {
try {
DisplayUtil.init(this);// 這個可以在應用程序起來的時候init
int size = data.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) data.get(i);
String key = o.getString(0);
String value = o.getString(1);
if (TextUtils.isEmpty(key) || TextUtils.isEmpty(value)) {
continue;
}
float curWidth = leftPaint.measureText(key);
if (curWidth > maxLeftWidth) {
maxLeftWidth = curWidth;
}
}
maxLeftWidth = maxLeftWidth + middlePadding;
maxRightWidth = DisplayUtil.screenWidth - DisplayUtil.dp2px(this, 32 + 10) - maxLeftWidth;
} catch (Exception e) {
}
}
private GridLayout createGridLayout() {
GridLayout layout = new GridLayout(this);
layout.setColumnCount(2);
//layout.setRowCount(5);
layout.setOrientation(GridLayout.HORIZONTAL);
return layout;
}
}
如果直接創建一個GridLayout，裡面添加每一項，如果描述過長都導致顯示不全，這個是系統的一個bug，計算的寬度有問題，因此需要對此方案進行更改。
更改方式為先計算左邊占用的最大寬度，在添加右邊的項時，設置布局參數控制最大的長度。
采用每一行一個布局，手動一行一行進行添加：
public class Typography5Activity extends BaseActivity {
public static void start(Context context) {
Intent intent = new Intent();
intent.setClass(context, Typography5Activity.class);
context.startActivity(intent);
}
private LinearLayout root;
private Paint leftPaint = new Paint();
private float textSize;
private float maxLeftWidth;
private int middlePadding = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
root = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.activity_typography5, null);
setContentView(root);
initPaint();
loadData();
}
private void initPaint() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
leftPaint.setAntiAlias(true);
leftPaint.setTextSize(textSize);
leftPaint.setColor(getResources().getColor(R.color.color_black_999999));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
private void loadData() {
JSONArray array = DataSource.getArray();
calculateLeftMaxWidth(array);
if (array != null) {
try {
int size = array.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) array.get(i);
String key = o.getString(0);
String value = o.getString(1);
addItem(key, value);
}
} catch (Exception e) {
}
}
}
private void calculateLeftMaxWidth(JSONArray data) {
try {
int size = data.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) data.get(i);
String key = o.getString(0);
String value = o.getString(1);
if (TextUtils.isEmpty(key) || TextUtils.isEmpty(value)) {
continue;
}
float curWidth = leftPaint.measureText(key);
if (curWidth > maxLeftWidth) {
maxLeftWidth = curWidth;
}
}
maxLeftWidth = maxLeftWidth + middlePadding;
} catch (Exception e) {
}
}
private void addItem(String key, String value) {
LinearLayout layout = getItemLayout();
TextView left = (TextView) layout.findViewById(R.id.left);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
params.width = (int) maxLeftWidth;
left.setLayoutParams(params);
left.setText(key);
TextView right = (TextView) layout.findViewById(R.id.right);
right.setText(value);
root.addView(layout);
}
private LinearLayout getItemLayout() {
LinearLayout layout = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.compose_item_layout, null);
return layout;
}
}
改方案也需要先計算左邊的最大占用寬度，來設置右邊占用的大小，每一項的布局如下：
每一行有兩個TextView，左邊寬度為自適應，右邊占據剩下左右的位置，在計算出左邊最大寬度後，重新設置左邊每一個TextView占用的寬度。
方式與1差不多，但是不在繼承TextView，而是直接繼承View:
public class TypographyView4 extends View {
private Paint leftPaint = new Paint();
private Paint rightPaint = new Paint();
private int fullWidth;
private float textSize;
private JSONArray array;
private int middlePadding = 0;
float maxLeftWidth = 0;
int itemSize = 0;
public TypographyView4(Context context) {
super(context);
init();
}
public TypographyView4(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TypographyView4(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
textSize = getResources().getDimensionPixelSize(R.dimen.text_size_13);
leftPaint.setAntiAlias(true);
leftPaint.setTextSize(textSize);
leftPaint.setColor(getResources().getColor(R.color.color_black_999999));
rightPaint.setAntiAlias(true);
rightPaint.setTextSize(textSize);
rightPaint.setColor(getResources().getColor(R.color.color_black));
middlePadding = getResources().getDimensionPixelSize(R.dimen.padding_value);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
fullWidth = getWidth();// 整個textView的寬度
}
public void setText(JSONArray array) {
this.array = array;
if (array != null) {
try {
int size = itemSize = array.length();
for (int i = 0; i < size; ++i) {
JSONArray o = (JSONArray) array.get(i);
String key = o.getString(0);
String value = o.getString(1);
if (TextUtils.isEmpty(key) || TextUtils.isEmpty(value)) {
itemSize--;
continue;
}
float curWidth = leftPaint.measureText(key);
if (curWidth > maxLeftWidth) {
maxLeftWidth = curWidth;
}
}
maxLeftWidth = maxLeftWidth + middlePadding;
invalidate();
} catch (Exception e) {
}
}
}
@Override
protected void onDraw(Canvas canvas) {
if (array == null) {
return;
}
int lineCount = 0;
try {
JSONArray item;
float offsetY;
for (int i = 0; i < itemSize; ++i) {
item = (JSONArray) array.get(i);
offsetY = (lineCount + 1) * textSize;
canvas.drawText(item.getString(0), 0, offsetY, leftPaint);
String value = item.getString(1);
float valueWidth = rightPaint.measureText(value);
if (valueWidth > fullWidth - maxLeftWidth) {// 一行顯示不完
char[] textCharArray = value.toCharArray();
float charWidth;
float drawWidth = maxLeftWidth;
for (int j = 0; j < textCharArray.length; j++) {
charWidth = rightPaint.measureText(textCharArray, j, 1);
if (fullWidth - drawWidth < charWidth) {
lineCount++;
drawWidth = maxLeftWidth;
offsetY += textSize;
}
canvas.drawText(textCharArray, j, 1, drawWidth, offsetY, rightPaint);
drawWidth += charWidth;
}
} else {
canvas.drawText(value, maxLeftWidth, offsetY, rightPaint);
}
lineCount += 2;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
該方案主要繼承自View，不再繼承TextView，由於在在上述方案中不在調用super，因此TextView已經退化為一個View,因此直接繼承View。
因為左邊的寬度不確定，因此所有的方案都進行了同樣的一個操作，就是測量了左邊顯示的最大寬度，後續的操作再根據該寬度進行調整。上述的方案中1，2，3，6都只需用一個View來進行顯示，4，5都需要多個View進行顯示。
Android如何適配雙卡
這裡僅以獲取sim卡的IMSI接口(getSubscriberId)和發短信接口(sendTextMessage)為例來詳細講解一下Android5.0-6.0雙卡適配的
Android VectorDrawable與SVG 實現炫酷動畫
Android 從 5.0 提供了新的API VectorDrawable,通過該對象，我們可以使用矢量圖SVG。在編寫xml文件中，通過關鍵的幾個標簽節點，,完成對SV
Android多媒體之VideoView視頻播放器
本文實例為大家分享了視頻播放器的兩種方式，供大家參考，具體內容如下1）、SurfaceView在布局文件中<?xml version=1.0 encodin
Android自定義日歷控件實例詳解
為什麼要自定義控件有時，原生控件不能滿足我們對於外觀和功能的需求，這時候可以自定義控件來定制外觀或功能；有時，原生控件可以通過復雜的編碼實現想要的功能，這時候可以自定義控
