下面是一个画各种图形的例子，具体的画图方法不用特别解释，看API就可以了

先定义一个继承自View的类DrawView

package WangLi.Graphics.MyView;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.view.View;

public class DrawView extends View {
    public DrawView(Context context,AttributeSet set)
    {
    	super(context,set);
    }
    @Override
    //重写该方法,进行绘图
    protected void onDraw(Canvas canvas)
    {
    	super.onDraw(canvas);
    	//把整张画布绘制成白色
    	canvas.drawColor(Color.WHITE);
    	Paint paint = new Paint();
    	//去锯齿
    	paint.setAntiAlias(true);
    	paint.setColor(Color.BLUE);
    	paint.setStyle(Paint.Style.STROKE);
    	paint.setStrokeWidth(3);
    	//绘制圆形
    	canvas.drawCircle(40, 40, 30, paint);
    	//绘制正方形
    	canvas.drawRect(10,80,70,140, paint);
    	//绘制矩形
    	canvas.drawRect(10,150,70,190, paint);
    	RectF re1 = new RectF(10,200,70,230);
    	//绘制圆角矩形
    	canvas.drawRoundRect(re1, 15, 15, paint);
    	RectF rel1 = new RectF(10,240,70,270);
    	//绘制椭圆
    	canvas.drawOval(rel1, paint);
    	//定义一个Path对象,封闭成一个三角形
    	Path path1 = new Path();
    	path1.moveTo(10, 340);
    	path1.lineTo(70, 340);
    	path1.lineTo(40, 290);
    	path1.close();
    	//根据path进行绘制,绘制三角形
    	canvas.drawPath(path1,paint);
    	
    	//根据path进行绘制,封闭成一个五角形
    	Path path2 = new Path();
    	path2.moveTo(26, 360);
    	path2.lineTo(54, 360);
    	path2.lineTo(70, 392);
    	path2.lineTo(40, 420);
    	path2.lineTo(10, 392);
    	path2.close();
    	//根据path进行绘制,绘制五角形
    	canvas.drawPath(path2,paint);
    	//-----------------设置填充风格后绘制------------------
    	paint.setStyle(Paint.Style.FILL);
    	paint.setColor(Color.RED);
    	canvas.drawCircle(120, 40, 30, paint);
    	//绘制正方形
    	canvas.drawRect(90, 80, 150, 140, paint);
    	//绘制矩形
    	canvas.drawRect(90, 150, 150, 190, paint);
    	RectF re2 = new RectF(90,200,150,230);
    	//绘制圆角矩形
    	canvas.drawRoundRect(re2, 15, 15, paint);
    	RectF re21 = new RectF(90,240,150,270);
    	//绘制椭圆
    	canvas.drawOval(re21, paint);
    	Path path3 = new Path();
    	path3.moveTo(90, 340);
    	path3.lineTo(150, 340);
    	path3.lineTo(120, 290);
    	path3.close();
    	//绘制三角形
    	canvas.drawPath(path3, paint);
    	Path path4 = new Path();
    	path4.moveTo(106, 360);
    	path4.lineTo(134, 360);
    	path4.lineTo(150, 392);
    	path4.lineTo(120, 420);
    	path4.lineTo(90, 392);
    	path4.close();
    	//绘制五角形
    	canvas.drawPath(path4, paint);
    	//-----------------设置渐变后绘制------------------
    	//为Paint设置渐变器
    	Shader mShader = new LinearGradient(0,0,40,60,
    			new int[]{
    			Color.RED,Color.GREEN,Color.BLUE,Color.YELLOW},
    			null,Shader.TileMode.REPEAT);
    	//为Paint设置渐变器
    	paint.setShader(mShader);
    	//设置阴影
    	paint.setShadowLayer(45, 10, 10, Color.GRAY);
    	//绘制圆形
    	canvas.drawCircle(200, 40, 30, paint);
    	//绘制正方形
    	canvas.drawRect(170, 80, 230, 140, paint);
    	//绘制矩形
    	canvas.drawRect(170, 150, 230, 190, paint);
    	RectF re3 = new RectF(170,200,230,230);
    	//绘制圆角矩形
    	canvas.drawRoundRect(re3, 15, 15, paint);
    	RectF re31 = new RectF(170,240,230,270);
    	//绘制椭圆
    	canvas.drawOval(re31, paint);
    	Path path5 = new Path();
    	path5.moveTo(170, 340);
    	path5.lineTo(230, 340);
    	path5.lineTo(200, 290);
    	path5.close();
    	//绘制三角形
    	canvas.drawPath(path5, paint);
    	Path path6 = new Path();
    	path6.moveTo(186, 360);
    	path6.lineTo(214, 360);
    	path6.lineTo(230, 392);
    	path6.lineTo(200, 420);
    	path6.lineTo(170, 392);
    	path6.close();
    	//绘制五角形
    	canvas.drawPath(path6, paint);
    }
}

再到main.xml中直接进行引用　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http:///apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" 
    android:id="@+id/root">
　　<WangLi.Graphics.MyView.DrawView android:layout_width="wrap_content" android:layout_height="wrap_content" /> 
</LinearLayout>

以上有填充，渐变，其实还可以放文字上去，例子上我就不弄了，很简单

canvas.drawText("some text",x,y,paint);

下面是运行的效果图