Java-类库-Guava-Throwables类

有时候, 当我们我们捕获异常, 并且像把这个异常传递到下一个try/catch块中。Guava提供了一个异常处理工具类, 可以简单地捕获和重新抛出多个异常。

[code]import java.io.IOException;
import org.junit.Test;
import com.google.common.base.Throwables;

public class ThrowablesTest {

    @Test
    public void testThrowables(){
        try {
            throw new Exception();
        } catch (Throwable t) {
            String ss = Throwables.getStackTraceAsString(t);
            System.out.println("ss:"+ss);
            Throwables.propagate(t);
        }
    }

    @Test
    public void call() throws IOException {
        try {
            throw new IOException();
        } catch (Throwable t) {
            Throwables.propagateIfInstanceOf(t, IOException.class);
            throw Throwables.propagate(t);
        }
    }    
}

将检查异常转换成未检查异常,例如：

[code]import java.io.InputStream;
import java.net.URL;
import org.junit.Test;
import com.google.common.base.Throwables;

public class ThrowablesTest {

    @Test
    public void testCheckException(){
        try {  
            URL url = new URL("http://ociweb.com");  
            final InputStream in = url.openStream();  
            // read from the input stream  
            in.close();  
        } catch (Throwable t) {  
            throw Throwables.propagate(t);  
        }  
    }
}

　传递异常的常用方法：

　　1.RuntimeException propagate(Throwable)：把throwable包装成RuntimeException，用该方法保证异常传递，抛出一个RuntimeException异常

　　2.void propagateIfInstanceOf(Throwable, Class) throws X：当且仅当它是一个X的实例时，传递throwable

　　3.void propagateIfPossible(Throwable)：当且仅当它是一个RuntimeException和Error时，传递throwable

　　4.void propagateIfPossible(Throwable, Class) throws X：当且仅当它是一个RuntimeException和Error时，或者是一个X的实例时，传递throwable。

[code]import java.io.IOException;
import org.junit.Test;
import com.google.common.base.Throwables;

public class ThrowablesTest {    
    @Test
    public void testThrowables(){
        try {
            throw new Exception();
        } catch (Throwable t) {
            String ss = Throwables.getStackTraceAsString(t);
            System.out.println("ss:"+ss);
            Throwables.propagate(t);
        }
    }

    @Test
    public void call() throws IOException {
        try {
            throw new IOException();
        } catch (Throwable t) {
            Throwables.propagateIfInstanceOf(t, IOException.class);
            throw Throwables.propagate(t);
        }
    }

    public Void testPropagateIfPossible() throws Exception {
          try {
              throw new Exception();
          } catch (Throwable t) {
            Throwables.propagateIfPossible(t, Exception.class);
            Throwables.propagate(t);
          }

          return null;
    }
}

　Guava的异常链处理方法：

　　1.Throwable getRootCause(Throwable)

　　2.List getCausalChain(Throwable)

　　3.String getStackTraceAsString(Throwable)

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