Spring JdbcTemplate.queryForList()
July 31, 2022
JdbcTemplate.queryForList() method. The queryForList() method executes the given SQL and returns result as List of objects.
The
queryForList() method accepts arguments in following ways.
1.
List<Map<String,Object>> queryForList(String sql) throws DataAccessException
PreparedStatement. The result list contains maps. One map instance represents one row where map key is column name and map value is column value.
2.
<T> List<T> queryForList(String sql, Class<T> elementType) throws DataAccessException
PreparedStatement. The result list contains the element of given element Type.
3.
<T> List<T> queryForList(String sql, Class<T> elementType, @Nullable Object... args) throws DataAccessException
4.
List<Map<String,Object>> queryForList(String sql, @Nullable Object... args) throws DataAccessException
5.
List<Map<String,Object>> queryForList(String sql, Object[] args, int[] argTypes) throws DataAccessException
6.
<T> List<T> queryForList(String sql, Object[] args, int[] argTypes, Class<T> elementType) throws DataAccessException
Parameters:
The sql is the SQL query to execute.
The args is the arguments to bind to the query.
The argTypes is the SQL types of the arguments i.e.
java.sql.Types.
The elementType is the required type of element in the result list.
Returns:
It returns a
List of objects.
Throws:
If the query fails, it throws
DataAccessException.
Example using Spring Boot
PersonDAO.java
package com.concretepage;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;
@Repository
public class PersonDAO {
@Autowired
private JdbcTemplate jdbcTemplate;
// queryForList(String sql)
public List<Person> getAllPersons() {
String sql = "select * from person";
List<Map<String,Object>> list = jdbcTemplate.queryForList(sql);
List<Person> plist = new ArrayList<>();
list.forEach(m -> {
Person p = new Person((String)m.get("name"), (Integer)m.get("age"));
p.setId((Integer)m.get("id"));
plist.add(p);
});
return plist;
}
// queryForList(String sql, Class<T> elementType)
public List<String> getAllNames() {
String sql = "select name from person";
List<String> list = jdbcTemplate.queryForList(sql, String.class);
List<String> plist = new ArrayList<>();
list.forEach(name -> plist.add(name));
return plist;
}
// queryForList(String sql, Class<T> elementType, Object... args)
public List<Integer> getIdsByNameNAge1(String name, int age) {
String sql = "select id from person where name = ? and age = ?";
List<Integer> list = jdbcTemplate.queryForList(sql, Integer.class, name, age);
List<Integer> plist = new ArrayList<>();
list.forEach(id -> plist.add(id));
return plist;
}
// queryForList(String sql, Object... args)
public List<Person> getPersonsByNameNAge1(String name, int age) {
String sql = "select * from person where name = ? and age = ?";
List<Map<String,Object>> list = jdbcTemplate.queryForList(sql, name, age);
List<Person> plist = new ArrayList<>();
list.forEach(m -> {
Person p = new Person((String)m.get("name"), (Integer)m.get("age"));
p.setId((Integer)m.get("id"));
plist.add(p);
});
return plist;
}
// queryForList(String sql, Object[] args, int[] argTypes)
public List<Person> getPersonsByNameNAge2(String name, int age) {
String sql = "select * from person where name = ? and age = ?";
Object[] args = { name, age };
int[] argTypes = { java.sql.Types.CHAR, java.sql.Types.INTEGER };
List<Map<String,Object>> list = jdbcTemplate.queryForList(sql, args, argTypes);
List<Person> plist = new ArrayList<>();
list.forEach(m -> {
Person p = new Person((String)m.get("name"), (Integer)m.get("age"));
p.setId((Integer)m.get("id"));
plist.add(p);
});
return plist;
}
// queryForList(String sql, Object[] args, int[] argTypes, Class<T> elementType)
public List<Integer> getIdsByNameNAge2(String name, int age) {
String sql = "select id from person where name = ? and age = ?";
Object[] args = { name, age };
int[] argTypes = { java.sql.Types.CHAR, java.sql.Types.INTEGER };
List<Integer> list = jdbcTemplate.queryForList(sql, args, argTypes, Integer.class);
List<Integer> plist = new ArrayList<>();
list.forEach(id -> plist.add(id));
return plist;
}
}
package com.concretepage;
public class Person {
private int id;
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return id + " - " + name + " - " + age;
}
}
spring.datasource.url=jdbc:mysql://localhost:3306/concretepage spring.datasource.username=root spring.datasource.password=cp spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>6.0.5</version> </dependency> </dependencies>
package com.concretepage;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(MyApplication.class, args);
PersonDAO personDAO = ctx.getBean(PersonDAO.class);
System.out.println(personDAO.getAllPersons()); // [1 - Rakesh - 30, 2 - Mohan - 25, 3 - Mohan - 25]
System.out.println(personDAO.getAllNames()); // [Rakesh, Mohan, Mohan]
System.out.println(personDAO.getIdsByNameNAge1("Mohan", 25)); // [2, 3]
System.out.println(personDAO.getPersonsByNameNAge1("Mohan", 25)); // [2 - Mohan - 25, 3 - Mohan - 25]
System.out.println(personDAO.getPersonsByNameNAge2("Mohan", 25)); // [2 - Mohan - 25, 3 - Mohan - 25]
System.out.println(personDAO.getIdsByNameNAge2("Mohan", 25)); // [2, 3]
}
}
