JDK1.7启动项目报错Unsupported major.minor version 52.0

Caused by: java.lang.UnsupportedClassVersionError: org/springframework/context/annotation/ClassPathBeanDefinitionScanner : Unsupported major.minor version 52.0 (unable to load class org.springframework.context.annotation.ClassPathBeanDefinitionScanner)

报错原因：运行环境的jdk版本低于项目需要的jdk版本

在构建项目时也可以得到提示：Warning:java: D:\mavenRepositories\Crm-UCCP\smp_com\V3.x\smp_com-V3.x.jar(com/tydic/smp/entity/UsersEntity.class): 主版本 52 比 51 新, 此编译器支持最新的主版本。
  建议升级此编译器。

解决方法：将jdk版本统一从1.7升级到1.8，具体过程就是在idea中对jdk版本的各种设置，这里就不记录了。

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jdk升级到1.8之后，重新启动项目报错：

Caused by: java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher

报错原因：Spring版本过低，不支持jdk1.8

解决方法：修改spring的jar包，在org.springframework.core目录下，有一个JdkVersion.class，自己参照包路径，重新写一个JdkVersion.java。

修改后的JdkVersion.java文件如下：

package org.springframework.core;
 
public class JdkVersion
{
    
    public static final int JAVA_13 = 0;
    
    public static final int JAVA_14 = 1;
    
    public static final int JAVA_15 = 2;
    
    public static final int JAVA_16 = 3;
    
    public static final int JAVA_17 = 4;
    
    //还可以参照该模板更改对更高版本JDK的支持
    //for jre 1.8
    public static final int JAVA_18 = 5;
    
    private static final String javaVersion = System.getProperty("java.version");
    
    private static final int majorJavaVersion;
    
    public static String getJavaVersion()
    {
        return javaVersion;
    }
    
    public static int getMajorJavaVersion()
    {
        return majorJavaVersion;
    }
    
    public static boolean isAtLeastJava14()
    {
        return true;
    }
    
    public static boolean isAtLeastJava15()
    {
        return getMajorJavaVersion() >= 2;
    }
    
    public static boolean isAtLeastJava16()
    {
        return getMajorJavaVersion() >= 3;
    }
    
    static
    {
        //for jre 1.8
        if (javaVersion.indexOf("1.8.") != -1)
        {
            majorJavaVersion = 5;
        }
        else if (javaVersion.indexOf("1.7.") != -1)
        {
            majorJavaVersion = 4;
        }
        else if (javaVersion.indexOf("1.6.") != -1)
        {
            majorJavaVersion = 3;
        }
        else if (javaVersion.indexOf("1.5.") != -1)
        {
            majorJavaVersion = 2;
        }
        else
        {
            majorJavaVersion = 1;
        }
    }
}