我想在控制台打印一些东西，这样我就可以调试它。但出于某种原因，我的Android应用程序没有打印任何东西。
我怎么调试呢?
public class HelloWebview extends Activity {
WebView webview;
private static final String LOG_TAG = "WebViewDemo";
private class HelloWebViewClient extends WebViewClient {
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
webview = (WebView) findViewById(R.id.webview);
webview.setWebViewClient(new HelloWebViewClient());
webview.getSettings().setJavaScriptEnabled(true);
webview.setWebChromeClient(new MyWebChromeClient());
webview.loadUrl("http://example.com/");
System.out.println("I am here");
}
如果你真的需要System.out.println工作(例如。它是从第三方库调用的)。你可以简单地使用反射来更改System.class中的out字段:
try{
Field outField = System.class.getDeclaredField("out");
Field modifiersField = Field.class.getDeclaredField("accessFlags");
modifiersField.setAccessible(true);
modifiersField.set(outField, outField.getModifiers() & ~Modifier.FINAL);
outField.setAccessible(true);
outField.set(null, new PrintStream(new RedirectLogOutputStream());
}catch(NoSuchFieldException e){
e.printStackTrace();
}catch(IllegalAccessException e){
e.printStackTrace();
}
RedirectLogOutputStream类:
public class RedirectLogOutputStream extends OutputStream{
private String mCache;
@Override
public void write(int b) throws IOException{
if(mCache == null) mCache = "";
if(((char) b) == '\n'){
Log.i("redirect from system.out", mCache);
mCache = "";
}else{
mCache += (char) b;
}
}
}
如果你真的需要System.out.println工作(例如。它是从第三方库调用的)。你可以简单地使用反射来更改System.class中的out字段:
try{
Field outField = System.class.getDeclaredField("out");
Field modifiersField = Field.class.getDeclaredField("accessFlags");
modifiersField.setAccessible(true);
modifiersField.set(outField, outField.getModifiers() & ~Modifier.FINAL);
outField.setAccessible(true);
outField.set(null, new PrintStream(new RedirectLogOutputStream());
}catch(NoSuchFieldException e){
e.printStackTrace();
}catch(IllegalAccessException e){
e.printStackTrace();
}
RedirectLogOutputStream类:
public class RedirectLogOutputStream extends OutputStream{
private String mCache;
@Override
public void write(int b) throws IOException{
if(mCache == null) mCache = "";
if(((char) b) == '\n'){
Log.i("redirect from system.out", mCache);
mCache = "";
}else{
mCache += (char) b;
}
}
}
