个人觉得JdbcTemplate相较于MyBaits，Hibernate等数据库框架更容易上手，对SQL的操作也更为直观方便，所以在项目中也是一个不错的选择。在Spring Boot开启JdbcTemplate很简单，只需要引入spring-boot-starter-jdbc依赖即可。JdbcTemplate封装了许多SQL操作，具体可查阅官方文档https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/jdbc/core/JdbcTemplate.html。

引入依赖

spring-boot-starter-jdbc：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

数据库驱动为ojdbc6，数据源采用Druid。具体可参考https://mrbird.cc/Spring-Boot%E4%B8%AD%E4%BD%BF%E7%94%A8Mybatis.html。

代码编写

数据准备：

CREATE TABLE "SCOTT"."STUDENT" (
    "SNO" VARCHAR2(3 BYTE) NOT NULL ,
    "SNAME" VARCHAR2(9 BYTE) NOT NULL ,
    "SSEX" CHAR(2 BYTE) NOT NULL 
);
INSERT INTO "SCOTT"."STUDENT" VALUES ('001', 'KangKang', 'M ');
INSERT INTO "SCOTT"."STUDENT" VALUES ('002', 'Mike', 'M ');
INSERT INTO "SCOTT"."STUDENT" VALUES ('003', 'Jane', 'F ');

这里主要演示在Dao的实现类里使用JdbcTemplate，所以其它模块代码的编写就不展示了，具体可参考文末的源码。

StudentDaoImp类代码：

@Repository("studentDao")
public class StudentDaoImp implements StudentDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;
    @Override
    public int add(Student student) {
        // String sql = "insert into student(sno,sname,ssex) values(?,?,?)";
        // Object[] args = { student.getSno(), student.getName(), student.getSex() };
        // int[] argTypes = { Types.VARCHAR, Types.VARCHAR, Types.VARCHAR };
        // return this.jdbcTemplate.update(sql, args, argTypes);
        String sql = "insert into student(sno,sname,ssex) values(:sno,:name,:sex)";
        NamedParameterJdbcTemplate npjt = new NamedParameterJdbcTemplate(this.jdbcTemplate.getDataSource());
        return npjt.update(sql, new BeanPropertySqlParameterSource(student));
    }
    @Override
    public int update(Student student) {
        String sql = "update student set sname = ?,ssex = ? where sno = ?";
        Object[] args = { student.getName(), student.getSex(), student.getSno() };
        int[] argTypes = { Types.VARCHAR, Types.VARCHAR, Types.VARCHAR };
        return this.jdbcTemplate.update(sql, args, argTypes);
    }
    @Override
    public int deleteBysno(String sno) {
        String sql = "delete from student where sno = ?";
        Object[] args = { sno };
        int[] argTypes = { Types.VARCHAR };
        return this.jdbcTemplate.update(sql, args, argTypes);
    }
    @Override
    public List<Map<String, Object>> queryStudentsListMap() {
        String sql = "select * from student";
        return this.jdbcTemplate.queryForList(sql);
    }
    @Override
    public Student queryStudentBySno(String sno) {
        String sql = "select * from student where sno = ?";
        Object[] args = { sno };
        int[] argTypes = { Types.VARCHAR };
        List<Student> studentList = this.jdbcTemplate.query(sql, args, argTypes, new StudentMapper());
        if (studentList != null && studentList.size() > 0) {
            return studentList.get(0);
        } else {
            return null;
        }
    }
}

在引入spring-boot-starter-jdbc驱动后，可直接在类中注入JdbcTemplate。由上面代码可发现，对于保存操作有两种不同的方法，当插入的表字段较多的情况下，推荐使用NamedParameterJdbcTemplate。

对于返回结果，可以直接使用List<Map<String, Object>>来接收，这也是个人比较推荐使用的方式，毕竟比较简单方便；也可以使用库表对应的实体对象来接收，不过这时候我们就需要手动创建一个实现了org.springframework.jdbc.core.RowMapper的对象，用于将实体对象属性和库表字段一一对应：

public class StudentMapper implements RowMapper<Student>{
    @Override
    public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
        Student student = new Student();
        student.setSno(rs.getString("sno"));
        student.setName(rs.getString("sname"));
        student.setSex(rs.getString("ssex"));
        return student;
    }
}

RowMapper问题

可以采用Spring提供的BeanPropertyRowMapper。这个mapper中在initialize初始化中会对Java属性名转化为数据库字段名。会在遇到大写字母X后转换为_x。

注意：如果数据库字段是A_XX这样，而属性名为aXx。如果使用IDEA自带的生成setter方法会生成setaXx就没有问题。如果使用lombok会生成setter字段：setAXx，就会不匹配，这个时候需要修改一下BeanPropertyRowMapper:

protected void initialize(Class<T> mappedClass) {
        this.mappedClass = mappedClass;
        this.mappedFields = new HashMap<String, PropertyDescriptor>();
        this.mappedProperties = new HashSet<String>();
        PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
        for (PropertyDescriptor pd : pds) {
            if (pd.getWriteMethod() != null) {
                this.mappedFields.put(lowerCaseName(pd.getName()), pd);
                String underscoredName = underscoreName(pd.getName());
                if (!lowerCaseName(pd.getName()).equals(underscoredName)) {
                    this.mappedFields.put(underscoredName, pd);
                }
                this.mappedProperties.add(pd.getName());
            }
        }
    }
   /**
     * Convert the given name to lower case.
     * By default, conversions will happen within the US locale.
     * @param name the original name
     * @return the converted name
     * @since 4.2
     */
    protected String lowerCaseName(String name) {
        return name.toLowerCase(Locale.US);
    }
    /**
     * Convert a name in camelCase to an underscored name in lower case.
     * Any upper case letters are converted to lower case with a preceding underscore.
     *
     * @param name the original name
     * @return the converted name
     * @see #lowerCaseName
     * @since 4.2
     */
    protected String underscoreName(String name) {
        if (!StringUtils.hasLength(name)) {
            return "";
        }
        StringBuilder result = new StringBuilder();
        result.append(lowerCaseName(name.substring(0, 1)));
        for (int i = 1; i < name.length(); i++) {
            String s = name.substring(i, i + 1);
            String slc = lowerCaseName(s);
            if (!s.equals(slc)) {
                result.append("_").append(slc);
            } else {
                result.append(s);
            }
        }
        return result.toString();
    }

对比原版的BeanPropertyRowMapper

/**
* Convert a name in camelCase to an underscored name in lower case.
* Any upper case letters are converted to lower case with a preceding underscore.
* @param name the original name
* @return the converted name
* @since 4.2
* @see #lowerCaseName
*/
protected String underscoreName(String name) {
    if (!StringUtils.hasLength(name)) {
        return "";
    }
    StringBuilder result = new StringBuilder();
    result.append(Character.toLowerCase(name.charAt(0)));
    for (int i = 1; i < name.length(); i++) {
        char c = name.charAt(i);
        if (Character.isUpperCase(c)) {
            result.append('_').append(Character.toLowerCase(c));
        }
        else {
            result.append(c);
        }
    }
    return result.toString();
    }

其中PropertyDescriptor[] ps = Introspector.getBeanInfo(bean.getClass()).getPropertyDescriptors()方法用于获取的类的属性。获取的属性不是类的成员变量。

public class demo {
    public String name;
    private String fOpen;
    public String getName() {
        return name;
    }
    public void setNameTest(String name) {
        this.name = name;
    }
    public String getfOpen() {
        return fOpen;
    }
    public void setfOpen(String fOpen) {
        this.fOpen = fOpen;
    }
    public static void main(String[] args) {
        try {
            PropertyDescriptor[] pds = Introspector.getBeanInfo(demo.class).getPropertyDescriptors();
            for(PropertyDescriptor pd : pds){
                System.out.println(pd.getName());
            }
        } catch (IntrospectionException e) {
            e.printStackTrace();
        }
    }