Android经过图片名字获得ID

package com.zhycheng;import android.R.drawable;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import com.zhycheng.R;public class TestClassActivity extends Activity implements OnClickListener {	Button b;	ImageView iv;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        b=(Button) findViewById(R.id.button1);        iv=(ImageView) findViewById(R.id.imageView1);        b.setOnClickListener(this);    }	@Override	public void onClick(View v) {		Class<com.zhycheng.R.drawable> cls = R.drawable.class;	    try {	        int value = cls.getDeclaredField("ic_launcher").getInt(null);	        iv.setBackgroundResource(value);	                    //Log.v("value",value.toString());	    } catch (Exception e) {	        // TODO Auto-generated catch block	        e.printStackTrace();	    } 			}}