自定义标题栏

先看看效果图

首先我们需要在values文件夹下新建一个attr.xml文件，保存我们自定义的属性

<resources>
    <declare-styleable name="TopBar">
        <attr name="tvTitle" format="string"/>
        <attr name="titleTextSize" format="dimension"/>
        <attr name="tvTitleTextColor" format="color"/>
        <attr name="leftText" format="string"/>
        <attr name="leftTextColor" format="color"/>
        <attr name="leftBackGround" format="reference|color"/>
        <attr name="rightText" format="string"/>
        <attr name="rightBackGround" format="reference|color"/>
        <attr name="rightTextColor" format="color"/>
    </declare-styleable>
</resources>

这里说一下值得注意的地方：
1.根节点是declare-styleable
2.name属性用来指定属性的前缀，我们再代码中获取自定义属性时会用到，格式是”前缀_属性名”,这个前缀名是可以任意取得，不过一般我们让它和控件名称相同，便于识别
3.format定义属性类型，如果是背景，可以使用format=”reference|color”，因为背景可以是引用，也可以是颜色

然后看我们的TopBar.java文件

public class TopBar extends RelativeLayout {
    private final Drawable mLeftBackground;
    private final int mLeftTextColor;
    private final String mLeftText;
    private final String mRigthText;
    private final Drawable mRightBackground;
    private final int mRightTextColor;
    private final int mColor;
    private final float mTvTitleSize;
    private final String mTvTitle;
    public OnTopBarClickListener mListener;
    private Button mRightButton;
    private Button mLeftButton;
    private TextView mTvTitle1;

    public interface OnTopBarClickListener{
        void leftClick();
        void rightClick();
    }

    public TopBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        //将declare-styleable中定义的属性值封装到typedArray中
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.TopBar);
        mTvTitle = typedArray.getString(R.styleable.TopBar_tvTitle);
        mTvTitleSize = typedArray.getDimension(R.styleable.TopBar_titleTextSize, 20);
        mColor = typedArray.getColor(R.styleable.TopBar_tvTitleTextColor, 0);
        mLeftText = typedArray.getString(R.styleable.TopBar_leftText);
        mLeftTextColor = typedArray.getColor(R.styleable.TopBar_leftTextColor, 0);
        mLeftBackground = typedArray.getDrawable(R.styleable.TopBar_leftBackGround);
        mRigthText = typedArray.getString(R.styleable.TopBar_rightText);
        mRightBackground = typedArray.getDrawable(R.styleable.TopBar_rightBackGround);
        mRightTextColor = typedArray.getColor(R.styleable.TopBar_rightTextColor, 0);
        //回收资源，以便下次使用，在这之后，不能使用typedArray
        typedArray.recycle();
        initChildView(context);
    }

    /**
     * 初始化控件
     * @param context
     */
    public void initChildView(Context context){
        mTvTitle1 = new TextView(context);
        mTvTitle1.setText(mTvTitle);
        mTvTitle1.setTextColor(mColor);
        mTvTitle1.setTextSize(mTvTitleSize);

        mLeftButton = new Button(context);
        mLeftButton.setText(mLeftText);
        mLeftButton.setBackground(mLeftBackground);
        mLeftButton.setTextColor(mLeftTextColor);

        mRightButton = new Button(context);
        mRightButton.setText(mRigthText);
        mRightButton.setTextColor(mRightTextColor);
        mRightButton.setBackground(mRightBackground);
        //设置布局参数
        RelativeLayout.LayoutParams leftParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.MATCH_PARENT);
        //设定布局规则
        leftParams.addRule(RelativeLayout.ALIGN_PARENT_LEFT,TRUE);
        addView(mLeftButton,leftParams);//添加到容器中

        RelativeLayout.LayoutParams titleParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,
                LayoutParams.WRAP_CONTENT);
        titleParams.addRule(RelativeLayout.CENTER_IN_PARENT,TRUE);
        addView(mTvTitle1, titleParams);

        RelativeLayout.LayoutParams rightParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,
                RelativeLayout.LayoutParams.MATCH_PARENT);
        rightParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT,TRUE);
        addView(mRightButton,rightParams);
        /**
         * 设置监听
         */
        mLeftButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mListener.leftClick();
            }
        });

        mRightButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                mListener.rightClick();
            }
        });
    }

    public void setOnTopBarClickListener(OnTopBarClickListener listener){
        mListener = listener;
    }

    /**
     * 设置可见性
     * @param leftState
     * @param rightState
     */
    public void setTopBarVisible(boolean leftState,boolean rightState){
        if(leftState){
            mLeftButton.setVisibility(VISIBLE);
        }else{
            mLeftButton.setVisibility(GONE);
        }
        if(rightState){
            mRightButton.setVisibility(VISIBLE);
        }else{
            mRightButton.setVisibility(GONE);
        }
    }
}

接下来我们再布局文件中定义这个标题栏布局

<?xml version="1.0" encoding="utf-8"?>
<com.example.administrator.myapplication.TopBar
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:custom="http://schemas.android.com/apk/res-auto"
    android:id="@+id/topbar"
    android:background="#ff0000"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    custom:tvTitle="自定标题栏"
    custom:titleTextSize="12sp"
    custom:tvTitleTextColor="#ff00ff"
    custom:leftText="返回"
    custom:leftBackGround="#0000ff"
    custom:leftTextColor="#000000"
    custom:rightText="提交"
    custom:rightTextColor="#FFFFFF"
    custom:rightBackGround="#00ff00"
    >
</com.example.administrator.myapplication.TopBar>

这里要注意，我们再attr.xml文件中使用的布局都要用到，否则就会出现某一个控件没法显示的问题

最后，在我们的布局文件中使用include包含这个标题栏就可以了

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.administrator.myapplication.MainActivity">
    <include layout="@layout/topbar"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="内容"
        />
</LinearLayout>

public class MainActivity extends AppCompatActivity {
    private TopBar mTopBar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTopBar = (TopBar) findViewById(R.id.topbar);
      mTopBar.setOnTopBarClickListener(new TopBar.OnTopBarClickListener() {
          @Override
          public void leftClick() {
              Toast.makeText(MainActivity.this, "返回", Toast.LENGTH_SHORT).show();
          }
          @Override
          public void rightClick() {
              Toast.makeText(MainActivity.this, "提交", Toast.LENGTH_SHORT).show();
          }
      });
        mTopBar.setTopBarVisible(true,true);
    }
}