Error:unsupported class file version 52.0问题的解决

     这个问题主要的原因是依赖包的编译版本比主程序的编译版本高，导致主程序无法正常编译或运行，解决这个问题无非两招：

     1、提升主程序的编译器版本，用最新的编译器编译主程序，这样就可以兼容那个依赖包

     2、降低依赖包的编译版本。比如maven，降低到1.6的方法是：

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.1</version>
  <configuration>
      <source>1.6</source>
      <target>1.6</target>
      <encoding>UTF8</encoding>
  </configuration>
</plugin>

另附打本地依赖包的配置：

<build>
        <sourceDirectory>src/main/java</sourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <defaultLibBundleDir>lib</defaultLibBundleDir>
                    <source>1.5</source>
                    <target>1.5</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix></classpathPrefix>
                            <mainClass>com.xx.xx.xx</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <executions>
                    <execution>
                        <id>copy</id>
                        <phase>install</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>
                                ${project.build.directory}
                            </outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>2.2</version>
                <configuration>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
    </build>