android中ColorStateList及StateListDrawable设置Selector

写过android的代码相信大家对Selector并不陌生吧，下面来看看这段xml文件是如何定义的

    <?xml version="1.0" encoding="utf-8" ?>
    <selector xmlns:android="http://schemas.android.com/apk/res/android">
      <!-- 触摸时并且当前窗口处于交互状态 -->
      <item android:state_pressed="true" android:state_window_focused="true" android:drawable= "@drawable/pic1" />
      <!--  触摸时并且没有获得焦点状态 -->
      <item android:state_pressed="true" android:state_focused="false" android:drawable="@drawable/pic2" />
      <!--选中时的图片背景-->
      <item android:state_selected="true" android:drawable="@drawable/pic3" />
      <!--获得焦点时的图片背景-->
      <item android:state_focused="true" android:drawable="@drawable/pic4" />
      <!-- 窗口没有处于交互时的背景图片 -->
      <item android:drawable="@drawable/pic5" />
    </selector>  

上面的代码估计很多人都会经常的使用到，除了在xml里面写之外，我们还可以在代码中通过ColorStateList和StateListDrawable来设置Selector,ColorStateList主要是用于颜色的状态，StateListDrawable这个主要是用于设置图片的状态，当然使用这种代码编写的方法我们可以动态设置TextView、Button、ImageView等组件在不同状态下的背景/前景显示效果。而不需要固定死。

package lab.sodino.statelist;

import android.app.Activity;
import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.StateListDrawable;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

/**
 * 对TextView设置ColorStateList使其在Normal、Pressed、Focused、Unable四种状态下显示不同的颜色。<br/>
 * StateListDrawable可直接使用图片应用在相似场合。
 */
public class ActColorStateList extends Activity implements OnClickListener {
    private TextView txtShow;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtShow = (TextView) findViewById(R.id.txtShow);
        txtShow.setText("Sodino\nNormal:0xffffffff\nPressed:0xffffff00\nFocused:0xff0000ff\nUnable:0xffff0000");
        txtShow.setTextColor(createColorStateList(0xffffffff, 0xffffff00, 0xff0000ff, 0xffff0000));
        txtShow.setOnClickListener(this);
    }

    /** 对TextView设置不同状态时其文字颜色。 */
    private ColorStateList createColorStateList(int normal, int pressed, int focused, int unable) {
        int[] colors = new int[] { pressed, focused, normal, focused, unable, normal };
        int[][] states = new int[6][];
        states[0] = new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled };
        states[1] = new int[] { android.R.attr.state_enabled, android.R.attr.state_focused };
        states[2] = new int[] { android.R.attr.state_enabled };
        states[3] = new int[] { android.R.attr.state_focused };
        states[4] = new int[] { android.R.attr.state_window_focused };
        states[5] = new int[] {};
        ColorStateList colorList = new ColorStateList(states, colors);
        return colorList;
    }

    /** 设置Selector。 */
    public static StateListDrawable newSelector(Context context, int idNormal, int idPressed, int idFocused,
            int idUnable) {
        StateListDrawable bg = new StateListDrawable();
        Drawable normal = idNormal == -1 ? null : context.getResources().getDrawable(idNormal);
        Drawable pressed = idPressed == -1 ? null : context.getResources().getDrawable(idPressed);
        Drawable focused = idFocused == -1 ? null : context.getResources().getDrawable(idFocused);
        Drawable unable = idUnable == -1 ? null : context.getResources().getDrawable(idUnable);
        // View.PRESSED_ENABLED_STATE_SET
        bg.addState(new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled }, pressed);
        // View.ENABLED_FOCUSED_STATE_SET
        bg.addState(new int[] { android.R.attr.state_enabled, android.R.attr.state_focused }, focused);
        // View.ENABLED_STATE_SET
        bg.addState(new int[] { android.R.attr.state_enabled }, normal);
        // View.FOCUSED_STATE_SET
        bg.addState(new int[] { android.R.attr.state_focused }, focused);
        // View.WINDOW_FOCUSED_STATE_SET
        bg.addState(new int[] { android.R.attr.state_window_focused }, unable);
        // View.EMPTY_STATE_SET
        bg.addState(new int[] {}, normal);
        return bg;
    }

    @Override
    public void onClick(View v) {
        if (v == txtShow) {
            txtShow.setEnabled(false);
        }
    }
}

我们看到在上面中出现 states[5] = new int[] {};和bg.addState(new int[] {}, normal);这些就是表示在不是上面任何一种状态的时候默认的值，像上面的这种状态android.R.attr.state_pressed，android.R.attr.state_enabled对应都是在xml中的值都是为true，即android:state_pressed="true"类似这个值，那么如果我这里想要设置为false时可以在前面加上一个　“－”负数的符号，比如bg.addState(new int[] {－android.R.attr.state_focused }, focused);那么这个就是表示state_focused＝false时的值为focused。

还有我们可以读取xml中设定的颜色值：比如

　ColorStateList　mIdleColorState = getResources().getColorStateList(idleStateSelector);

　int colorNormal＝colorStateList.getColorForState(new int[]{android.R.attr.state_enabled}, 0);

　int colorDisabled＝colorStateList.getColorForState(new int[]{-android.R.attr.state_enabled}, 0);//“-”负号表示对应的属性值为false