Android JNI 调用演示代码

package study.jnidemo; import android.app.Activity; import android.app.AlertDialog; import android.os.Bundle; import android.widget.Button; import android.view.View; import android.widget.TextView; import android.content.Context; import android.content.DialogInterface; public class JniDemoActivity extends Activity { public String strTest = " [initial message]"; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); findAndModifyButton(); } public String getTestString() { return strTest; } // 测试JAVA的NDK调用 public native String stringFromJNI(); // 测试C/C++中对JAVA函数的静态回调 public native static int jniStaticShowMessage(Context ctx, String strTitle, String strMessage); // 测试实例中C/C++中对JAVA类的函数的调用 public native int jniShowMessage(Context ctx, String strTitle, String strMessage); // 测试创建新实例C/C++对JAVA类的函数的调用 public native int jniInstanceShowMessage(Context ctx, String strTitle, String strMessage); static { System.loadLibrary("demo-jni"); } static int staticShowMessage(Context ctx, String strTitle, String strMessage) { AlertDialog.Builder builder = new AlertDialog.Builder(ctx); builder.setTitle(strTitle); builder.setMessage(strMessage); builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){ public void onClick(DialogInterface dialog, int whichButton){ } }); builder.show(); return 0; } public int showMessage(Context ctx, String strTitle, String strMessage) { return staticShowMessage(ctx, strTitle, strMessage); } private void findAndModifyButton() { // 测试JAVA的NDK调用 Button btn01 = (Button)findViewById(R.id.Button01); btn01.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { TextView tv = (TextView)findViewById(R.id.tv01); tv.setText(stringFromJNI()); showMessage(JniDemoActivity.this, "JNI test1", stringFromJNI()); } }); // 测试C/C++中对JAVA函数的静态回调 Button btn02 = (Button)findViewById(R.id.Button02); btn02.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { int ret = jniStaticShowMessage(JniDemoActivity.this, "JNI test2", "test static callback Message"); TextView tv = (TextView)findViewById(R.id.tv01); if(ret == 0) { tv.setText("test JNI static callback successed"); } else { tv.setText("test JNI static callback fialed"); } } }); // 测试实例中C/C++中对JAVA类的函数的调用 Button btn03 = (Button)findViewById(R.id.Button03); btn03.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { strTest = " [message has changed now]"; int ret = jniShowMessage(JniDemoActivity.this, "JNI test3", "test callback in current instance"); TextView tv = (TextView)findViewById(R.id.tv01); if(ret == 0) { tv.setText("test JNI callback successed"); } else { tv.setText("test JNI callback fialed"); } } }); // 测试创建新实例C/C++对JAVA类的函数的调用 Button btn04 = (Button)findViewById(R.id.Button04); btn04.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { strTest = " [message has changed now]"; int ret = jniInstanceShowMessage(JniDemoActivity.this, "JNI test4", "test callback in new instance"); TextView tv = (TextView)findViewById(R.id.tv01); if(ret == 0) { tv.setText("test JNI new instance successed"); } else { tv.setText("test JNI new instance fialed"); } } }); } }