简化异常处理的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。例如：

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：

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<X extends Exception>) 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<X extends Throwable>) 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。

　　使用实例：

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<Throwable> getCausalChain(Throwable)
　　3.String getStackTraceAsString(Throwable)

来源： http://www.cnblogs.com/peida/p/Guava_Throwables.html