使用a标签或form的submit做下载按钮，然后通过js调用其click事件去下载时经常出现的异常

异常：

ClientAbortException:  java.net.SocketException: Connection reset by peer: socket write error
at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBuffer.java:366)
at org.apache.tomcat.util.buf.ByteChunk.flushBuffer(ByteChunk.java:432)
at org.apache.tomcat.util.buf.ByteChunk.append(ByteChunk.java:347)
at org.apache.catalina.connector.OutputBuffer.writeBytes(OutputBuffer.java:392)
at org.apache.catalina.connector.OutputBuffer.write(OutputBuffer.java:381)
at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:89)
at com.joejoe.utils.IOUtils.write(IOUtils.java:62)
at com.joejoe.utils.IOUtils.write(IOUtils.java:48)
at com.tqsoft.wdys.other.getMegavideo.doGet(getMegavideo.java:79)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at com.joejoe.utils.web.CharSetFilter.doFilter(CharSetFilter.java:39)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at org.apache.coyote.http11.InternalOutputBuffer.realWriteBytes(InternalOutputBuffer.java:750)
at org.apache.tomcat.util.buf.ByteChunk.flushBuffer(ByteChunk.java:432)
at org.apache.tomcat.util.buf.ByteChunk.append(ByteChunk.java:347)
at org.apache.coyote.http11.InternalOutputBuffer$OutputStreamOutputBuffer.doWrite(InternalOutputBuffer.java:773)
at org.apache.coyote.http11.filters.IdentityOutputFilter.doWrite(IdentityOutputFilter.java:118)
at org.apache.coyote.http11.InternalOutputBuffer.doWrite(InternalOutputBuffer.java:583)
at org.apache.coyote.Response.doWrite(Response.java:560)
at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBuffer.java:361)
... 27 more

1：如果使用a标签，通常会直接将超链接的href设为下载地址，然后通过js调用其click事件去实现下载，经常出现以上异常。因为当我们点击的时候本身超链接的href本身应经定向到下载地址，而后而后js有调用了a的click事件导致了又执行了一次href所以出现两次下载请求，抛出连接被重置的异常

2：若在form里用了脚本提交，而在那个Form里面又用了submit了，这样会重复提交也会导致这种问题的。

注意：为了避免以上两种情况出现，我们最好使用button做下载按钮

3：可能防火墙或服务器连接数过小被使用完未关闭，也会导致该异常