控件：TouchProject（绘图） 触摸事件

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" 
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <org.lxh.demo.MyPaintView
        android:id="@+id/paintView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>
</LinearLayout>

MyPaintView.java

package org.lxh.demo;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class MyPaintView extends View {
    // 保存所有的操作坐标
    private List<Point> allPoint = new ArrayList<Point>(); 
    // 接收Context，同时接收属性集合
    public MyPaintView(Context context, AttributeSet attrs) { 
        // 调用父类的构造
        super(context, attrs); 
        super.setOnTouchListener(new OnTouchListenerImpl());
    }

    private class OnTouchListenerImpl implements OnTouchListener {
        public boolean onTouch(View v, MotionEvent event) {
             // 将坐标保存在Point类
            Point p = new Point((int) event.getX(), (int) event.getY());
            // 按下，表示重新开始保存点
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                // 重绘
                MyPaintView.this.allPoint = new ArrayList<Point>(); 
                // 保存点
                MyPaintView.this.allPoint.add(p); 
            // 用户松开
            } else if (event.getAction() == MotionEvent.ACTION_UP) { 
                // 记录坐标点
                MyPaintView.this.allPoint.add(p); 
                // 重绘图形
                MyPaintView.this.postInvalidate(); 
                // 用户移动
            } else if (event.getAction() == MotionEvent.ACTION_MOVE) { 
                // 记录坐标点
                MyPaintView.this.allPoint.add(p); 
                // 重绘图形
                MyPaintView.this.postInvalidate();
            }
            return true; // 表示下面的操作不再执行了。
        }
    }

    @Override
    protected void onDraw(Canvas canvas) { // 进行绘图
        // 依靠此类开始画线
        Paint p = new Paint();
        // 定义图的颜色
        p.setColor(Color.RED);
        // 现在有坐标点保存的时候可以开始进行绘图
        if (MyPaintView.this.allPoint.size() > 1) { 
            Iterator<Point> iter = MyPaintView.this.allPoint.iterator();
            Point first = null;
            Point last = null;
            while (iter.hasNext()) {
                if (first == null) {
                    // 取出坐标
                    first = (Point) iter.next(); 
                } else {
                    // 前一阶段已经完成了
                    if (last != null) { 
                        // 重新开始下一阶段
                        first = last; 
                    }
                    // 结束点坐标
                    last = (Point) iter.next(); 
                    canvas.drawLine(first.x, first.y, last.x, last.y, p);
                }
            }
        }
    }

}

MyTouchDemo.java

package org.lxh.demo;

import android.app.Activity;
import android.os.Bundle;

public class MyTouchDemo extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.main);
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="org.lxh.demo"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="5" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".MyTouchDemo"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>