不能从静态上下文中引用非静态变量角色 - JDO Querydsl

Question

我正在使用 JDO、Querydsl 构建一个 Maven 项目。但是在我的 DaoImpl class 一行显示错误是："non-static variable role cannot be referenced from a static context"

我的 pojo class 是： User.java

@PersistenceCapable(table="User_Login")
public class User {
@PrimaryKey
@Column(name="user_id")
private Integer userId=0;
@Column(name="user_profile_name")
private String userProfileName=null;  
@Column(name="user_email")
private String userEmail=null;
@Column(name="user_contact")
private String userContact=null;
@Column(name="user_name")
private String userName=null;
@Column(name="user_password")
private String userPassword=null;
@Column(name="user_role_id")
private Integer userRoleId=0;

private Role userRole=null;

Role.java:

   @PersistenceCapable(table="User_Role")
    public class Role {
    @PrimaryKey
    @Column(name="id")
    private Integer roleId=0;
    @Column(name="role")
    private String role=null;

我需要的结果是：

用户 ID：1，角色：admin

我的 DAOImpl class:

public List<User> getUser(String user_name, String user_password) {
    PersistenceManager pm =  
       this.persistenceManagerFactory.getPersistenceManager();
    Transaction tx = pm.currentTransaction();     
    SQLTemplates templates = new MySQLTemplates();         
    QUser user = QUser.user;
    QRole role = QRole.role;-----------**this is showing error**      
    JDOSQLQuery query = new JDOSQLQuery(pm, templates);
    try {
    // Start the transaction
    tx.begin(); 
    List<User> result = query.from(user)
                  .innerJoin(role).on(user.userRoleId.eq(role.roleId))
                  .where(user.userName.eq(user_name), 
             user.userPassword.eq(user_password)).
             list(user);               
    query.close();
    tx.commit();
    return result;
    }
    finally {
        if (tx.isActive())
        {
            // Error occurred so rollback the transaction
            tx.rollback();
        }
        pm.close();
    }

我的pom.xml是：

    <project xmlns="http://maven.apache.org/POM/4.0.0"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
       http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.titas</groupId>
<artifactId>QuerydslJDO</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>

<name>QuerydslJDO</name>

<properties>
    <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-web-api</artifactId>
        <version>6.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
    </dependency> 
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.1</version>
        <scope>provided</scope>
    </dependency>
    <dependency> 
        <groupId>jstl</groupId> 
        <artifactId>jstl</artifactId> 
        <version>1.2</version> 
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>4.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>4.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>4.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>4.1.6.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.6</version>
    </dependency> 
    <dependency>
        <groupId>javax.jdo</groupId>
        <artifactId>jdo-api</artifactId>
        <version>3.0.1</version>
    </dependency>
    <dependency>
        <groupId>com.mysema.querydsl</groupId>
        <artifactId>querydsl-apt</artifactId>
        <version>3.6.3</version>
        <scope>provided</scope>
    </dependency>            
    <dependency>
      <groupId>com.mysema.querydsl</groupId>
      <artifactId>querydsl-jdo</artifactId>
      <version>3.6.3</version>
    </dependency>
    <dependency>
        <groupId>com.mysema.querydsl</groupId>
        <artifactId>querydsl-sql</artifactId>
        <version>3.6.3</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>1.6.1</version>
    </dependency> 
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
                <compilerArguments>
                    <endorseddirs>${endorsed.dir}</endorseddirs>
                </compilerArguments>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>2.1.1</version>
            <configuration>
                <failOnMissingWebXml>false</failOnMissingWebXml>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.1</version>
            <executions>
                <execution>
                    <phase>validate</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${endorsed.dir}
                        </outputDirectory>
                        <silent>true</silent>
                        <artifactItems>
                            <artifactItem>
                                <groupId>javax</groupId>
                                <artifactId>javaee-endorsed-
                                 api</artifactId>
                                <version>6.0</version>
                                <type>jar</type>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin> 
        <plugin>
            <groupId>com.mysema.maven</groupId>
            <artifactId>apt-maven-plugin</artifactId>
            <version>1.0.4</version>
            <executions>
              <execution>
                <goals>
                  <goal>process</goal>
                </goals>
                <configuration>
                  <outputDirectory>target/generated-sources
                   /java</outputDirectory>
                  <processor>com.mysema.query.apt.jdo.
                   JDOAnnotationProcessor</processor>
                </configuration>
              </execution>
            </executions>
        </plugin> 
        <plugin>
            <groupId>com.mysema.querydsl</groupId>
            <artifactId>querydsl-maven-plugin</artifactId>
            <version>2.9.0</version>
            <executions>
              <execution>
                <goals>
                  <goal>export</goal>
                </goals>
              </execution>            
            </executions>
            <configuration>
              <jdbcDriver>com.mysql.jdbc.Driver</jdbcDriver>
              <jdbcUrl>jdbc:mysql://localhost:3306/login</jdbcUrl>
              <jdbcUser>root</jdbcUser>
              <packageName>com.titas.model</packageName>
              <targetFolder>${project.basedir}/target/generated-sources
               /java</targetFolder> 
            </configuration>
            <dependencies>
              <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>5.1.6</version>
              </dependency>
            </dependencies>
        </plugin>        
    </plugins>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
        </resource>
    </resources>
</build>

Answer 1

由于您的 Role.java 已经包含一个属性 'role' Querydsl 无法将您的标准变量生成为 'QRole.role'，因此它被命名为 'QRole.role1'.

不能从静态上下文中引用非静态变量角色 - JDO Querydsl

non-static variable role cannot be referenced from a static context- JDO Querydsl

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