我正在制作一个简单的演示，我可以在我的活动中将相机预览提供给SurfaceView。我发现如果你没有设置支持的大小，setParameters（）会失败。但即使我这样做，我也得到同样的致命异常。请帮忙！
代码：
package ank.altcamera;
import java.io.IOException;
import java.util.List;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.Switch;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.Size;
public class CameraActivity extends Activity implements SurfaceHolder.Callback{
Switch sw_flash;
SeekBar sb_zoom;
Camera cam;
SurfaceView surf_view;
SurfaceHolder surf_holder;
boolean preview;
final int TAKE_PICTURE = 100;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
sw_flash = (Switch) findViewById(R.id.sw_flash);
sb_zoom = (SeekBar) findViewById(R.id.seekBar1);
//camera settings
surf_view = (SurfaceView) findViewById(R.id.surfaceView);
surf_holder = surf_view.getHolder();
surf_holder.addCallback(CameraActivity.this);
}
/* Must implement Interface methods */
//onClickListener for the button
public void takePicture (View v) {
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
if (preview) {
cam.stopPreview();
}
Camera.Parameters p = cam.getParameters();
//check for supported sizes to avoid exceptions
Size size = getBestPreviewSize(width, height, p);
p.setPreviewSize(size.width, size.height);
//move ahead
p.setPreviewFormat(ImageFormat.JPEG);
cam.setParameters(p);
//start the preview
try {
cam.setPreviewDisplay(surf_holder);
cam.startPreview();
preview = true;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
cam = Camera.open();
if (cam != null){
Camera.Parameters params = cam.getParameters();
cam.setParameters(params);
}
else {
Toast.makeText(getApplicationContext(), "Camera error.", Toast.LENGTH_LONG).show();
finish();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
cam.stopPreview();
preview = false;
cam.release();
}
private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters){
Size bestSize = null;
List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();
bestSize = sizeList.get(0);
for(int i = 1; i < sizeList.size(); i++){
if((sizeList.get(i).width * sizeList.get(i).height) >
(bestSize.width * bestSize.height)){
bestSize = sizeList.get(i);
}
}
return bestSize;
}
}
这是我的布局XML文件：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/background_main"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".CameraActivity" >
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginBottom="18dp"
android:minWidth="100dp"
android:text="Awesome Camera"
android:textColor="#fff"
android:textSize="25sp"
android:textStyle="bold" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="10dp"
android:layout_marginTop="5dp"
android:text="Zoom"
android:textColor="#fff"
android:textStyle="bold" />
<SeekBar
android:id="@+id/seekBar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp" />
</LinearLayout>
<Switch
android:id="@+id/sw_flash"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Flash"
android:textColor="#fff"
android:textStyle="bold" />
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="20dp"
/>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="20dp"
android:background="#fff"
android:onClick="takePicture"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:text="Take Picture" />
</LinearLayout>
最后，logcat输出：
06-22 10:26:50.421: D/TextLayoutCache(12360): Using debug level: 0 - Debug Enabled: 0
06-22 10:26:50.511: D/libEGL(12360): loaded /system/lib/egl/libGLES_android.so
06-22 10:26:50.561: D/libEGL(12360): loaded /system/lib/egl/libEGL_adreno200.so
06-22 10:26:50.601: D/libEGL(12360): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
06-22 10:26:50.601: D/libEGL(12360): loaded /system/lib/egl/libGLESv2_adreno200.so
06-22 10:26:50.701: I/Adreno200-EGLSUB(12360): <ConfigWindowMatch:2218>: Format RGBA_8888.
06-22 10:26:50.711: D/memalloc(12360): /dev/pmem: Mapped buffer base:0x516f6000 size:5775360 offset:4239360 fd:58
06-22 10:26:50.711: D/OpenGLRenderer(12360): Enabling debug mode 0
06-22 10:26:51.491: D/AndroidRuntime(12360): Shutting down VM
06-22 10:26:51.491: W/dalvikvm(12360): threadid=1: thread exiting with uncaught exception (group=0x40c28a68)
06-22 10:26:51.501: E/AndroidRuntime(12360): FATAL EXCEPTION: main
06-22 10:26:51.501: E/AndroidRuntime(12360): java.lang.RuntimeException: setParameters failed
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.hardware.Camera.native_setParameters(Native Method)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.hardware.Camera.setParameters(Camera.java:1476)
06-22 10:26:51.501: E/AndroidRuntime(12360): at ank.altcamera.CameraActivity.surfaceChanged(CameraActivity.java:71)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.SurfaceView.updateWindow(SurfaceView.java:591)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.SurfaceView.access$000(SurfaceView.java:81)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:173)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:590)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1799)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2632)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.os.Handler.dispatchMessage(Handler.java:99)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.os.Looper.loop(Looper.java:137)
06-22 10:26:51.501: E/AndroidRuntime(12360): at android.app.ActivityThread.main(ActivityThread.java:4517)
06-22 10:26:51.501: E/AndroidRuntime(12360): at java.lang.reflect.Method.invokeNative(Native Method)
06-22 10:26:51.501: E/AndroidRuntime(12360): at java.lang.reflect.Method.invoke(Method.java:511)
06-22 10:26:51.501: E/AndroidRuntime(12360): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
06-22 10:26:51.501: E/AndroidRuntime(12360): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
06-22 10:26:51.501: E/AndroidRuntime(12360): at dalvik.system.NativeStart.main(Native Method)
06-22 10:27:00.301: I/Process(12360): Sending signal. PID: 12360 SIG: 9
请帮帮我！
答案 0 :(得分：8)
documentation表示setParameters在任何参数无效或不受支持时抛出RuntimeException。
您要更改的参数是大小和格式;但是，您从getSupportedPreviewSizes获取大小，因此它们一定不是问题所在。我想问题出在setPreviewFormat(ImageFormat.JPEG)。
答案 1 :(得分：4)
此错误始终很重要，请务必检查相机要求设置的所有参数，以确保您要求相机将自己设置为的每个参数都可用于相机。
Camera.Parameters parameters = myCamera.getParameters();
预览尺寸：
if (myCamera.getParameters().getSupportedPreviewSizes() != null){
Camera.Size previewSize = getOptimalPreviewSize(myCamera.getParameters().getSupportedPreviewSizes(), width, height);;
parameters.setPreviewSize(previewSize.width, previewSize.height);
}
使用闪光/对焦模式：
if(parameters.getSupportedFocusModes() != null && parameters.getSupportedFocusModes().contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)){
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
}
if (parameters.getSupportedFlashModes() != null && parameters.getSupportedFlashModes().contains(Camera.Parameters.FLASH_MODE_AUTO)){
parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
}
myCamera.setParameters(parameters);
等。所有这些都包含在一个很好的try {} catch（）{}中。祝你好运。
以下是来自this great tutorial的getOptimalPreview尺寸：
private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int width, int height)
{
// Source: http://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
Camera.Size optimalSize = null;
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) height / width;
// Try to find a size match which suits the whole screen minus the menu on the left.
for (Camera.Size size : sizes){
if (size.height != width) continue;
double ratio = (double) size.width / size.height;
if (ratio <= targetRatio + ASPECT_TOLERANCE && ratio >= targetRatio - ASPECT_TOLERANCE){
optimalSize = size;
}
}
// If we cannot find the one that matches the aspect ratio, ignore the requirement.
if (optimalSize == null) {
// TODO : Backup in case we don't get a size.
}
return optimalSize;
}
答案 2 :(得分：0)
您无法从它显示的消息文本中判断哪个参数导致运行时异常。 你最好逐个检查参数。