java通过lambda表达式实现简化代码

之前，调用第3方服务，每个方法都差不多“长”这样, 写起来啰嗦, 改起来麻烦, 还容易改漏。

public void authorizeroletouser(long userid, list<long> roleids) {
  try {
      power.authorizeroletouser(userid, roleids);
  } catch (motancustomexception ex) {
      if (ex.getcode().equals(msuserexception.notlogin().getcode()))
          throw userexception.notlogin();
      if (ex.getcode().equals(mspowerexception.havenopower().getcode()))
          throw powerexception.havenopower();
      throw ex;
  } catch (motanserviceexception ex) {
      cathelper.logeventservice("power-authorizeroletouser", "authorizeroletouser", ex.getstatus(),
              ex.geterrorcode(), ex.getmessage());
      throw ex;
  } catch (motanabstractexception ex) {
      cathelper.logeventservice("power-authorizeroletouser", "authorizeroletouser", ex.getstatus(),
              ex.geterrorcode(), ex.getmessage());
      throw ex;
  } catch (exception ex) {
      cathelper.logerror(ex);
      throw ex;
  }
}

我经过学习和提取封装, 将try ... catch ... catch .. 提取为公用, 得到这2个方法:

import java.util.function.supplier;
public static <t> t trycatch(supplier<t> supplier, string servicename, string methodname) {
  try {
      return supplier.get();
  } catch (motancustomexception ex) {
      if (ex.getcode().equals(msuserexception.notlogin().getcode()))
          throw userexception.notlogin();
      if (ex.getcode().equals(mspowerexception.havenopower().getcode()))
          throw powerexception.havenopower();
      throw ex;
  } catch (motanserviceexception ex) {
      cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
              ex.getmessage());
      throw ex;
  } catch (motanabstractexception ex) {
      cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
              ex.getmessage());
      throw ex;
  } catch (exception ex) {
      cathelper.logerror(ex);
      throw ex;
  }
}
public static void trycatch(runnable runnable, string servicename, string methodname) {
  trycatch(() -> {
      runnable.run();
      return null;
  }, servicename, methodname);
}

现在用起来是如此简洁。像这种无返回值的:

public void authorizeroletouser(long userid, list<long> roleids) {
  trycatch(() -> { power.authorizeroletouser(userid, roleids); }, "power", "authorizeroletouser");
}

还有这种有返回值的:

public list<roledto> listrolebyuser(long userid) {
  return trycatch(() -> power.listrolebyuser(userid), "power", "listrolebyuser");
}

后来发现以上2个方法还不够用, 原因是有一些方法会抛出 checked 异常, 于是又再添加了一个能处理异常的, 这次意外发现java的throws也支持泛型, 赞一个:

public static <t, e extends throwable> t trycatchexception(supplierexception<t, e> supplier, string servicename,
      string methodname) throws e {
  try {
      return supplier.get();
  } catch (motancustomexception ex) {
      if (ex.getcode().equals(msuserexception.notlogin().getcode()))
          throw userexception.notlogin();
      if (ex.getcode().equals(mspowerexception.havenopower().getcode()))
          throw powerexception.havenopower();
      throw ex;
  } catch (motanserviceexception ex) {
      cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
              ex.getmessage());
      throw ex;
  } catch (motanabstractexception ex) {
      cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
              ex.getmessage());
      throw ex;
  } catch (exception ex) {
      cathelper.logerror(ex);
      throw ex;
  }
}
@functionalinterface
public interface supplierexception<t, e extends throwable> {
  /**
   * gets a result.
   *
   * @return a result
   */
  t get() throws e;
}

为了不至于维护两份catch集, 将原来的带返回值的trycatch改为调用trycatchexception:

public static <t> t trycatch(supplier<t> supplier, string servicename, string methodname) {
  return trycatchexception(() -> supplier.get(), servicename, methodname);
}

这个世界又完善了一步。

前面制作了3种情况:

1.无返回值,无 throws

2.有返回值,无 throws

3.有返回值,有 throws

不确定会不会出现“无返回值，有throws“的情况。后来真的出现了！依样画葫芦，弄出了这个：

public static <e extends throwable> void trycatchexception(runnableexception<e> runnable, string servicename,
      string methodname) throws e {
  trycatchexception(() -> {
      runnable.run();
      return null;
  }, servicename, methodname);
}
@functionalinterface
public interface runnableexception<e extends throwable> {
  void run() throws e;
}

完整代码

package com.company.system.util;
import java.util.function.supplier;
import org.springframework.beans.factory.beancreationexception;
import com.company.cat.monitor.cathelper;
import com.company.system.customexception.powerexception;
import com.company.system.customexception.serviceexception;
import com.company.system.customexception.userexception;
import com.company.hyhis.ms.user.custom.exception.mspowerexception;
import com.company.hyhis.ms.user.custom.exception.msuserexception;
import com.company.hyhis.ms.user.custom.exception.motancustomexception;
import com.weibo.api.motan.exception.motanabstractexception;
import com.weibo.api.motan.exception.motanserviceexception;
public class thirdparty {
  public static void trycatch(runnable runnable, string servicename, string methodname) {
      trycatch(() -> {
          runnable.run();
          return null;
      }, servicename, methodname);
  }
  public static <t> t trycatch(supplier<t> supplier, string servicename, string methodname) {
      return trycatchexception(() -> supplier.get(), servicename, methodname);
  }
  public static <e extends throwable> void trycatchexception(runnableexception<e> runnable, string servicename,
          string methodname) throws e {
      trycatchexception(() -> {
          runnable.run();
          return null;
      }, servicename, methodname);
  }
  public static <t, e extends throwable> t trycatchexception(supplierexception<t, e> supplier, string servicename,
          string methodname) throws e {
      try {
          return supplier.get();
      } catch (motancustomexception ex) {
          if (ex.getcode().equals(msuserexception.notlogin().getcode()))
              throw userexception.notlogin();
          if (ex.getcode().equals(mspowerexception.havenopower().getcode()))
              throw powerexception.havenopower();
          throw ex;
      } catch (motanserviceexception ex) {
          cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
                  ex.getmessage());
          throw ex;
      } catch (motanabstractexception ex) {
          cathelper.logeventservice(servicename + "-" + methodname, methodname, ex.getstatus(), ex.geterrorcode(),
                  ex.getmessage());
          throw ex;
      } catch (exception ex) {
          cathelper.logerror(ex);
          throw ex;
      }
  }
  @functionalinterface
  public interface runnableexception<e extends throwable> {
      void run() throws e;
  }
  @functionalinterface
  public interface supplierexception<t, e extends throwable> {
      t get() throws e;
  }
}

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