Java Spring:用于动态查询的通用行映射器
我正在使用SpringBatch从Oracle读取数据并写入ElasticSearch 我的代码可以很好地用于静态查询。 示例:Java Spring:用于动态查询的通用行映射器,java,spring,spring-batch,Java,Spring,Spring Batch,我正在使用SpringBatch从Oracle读取数据并写入ElasticSearch 我的代码可以很好地用于静态查询。 示例:从employee_表中选择emp_id、emp_name我有一个行映射器类,它将resultSet中的值映射到employee POJO 我的要求是 查询将由用户输入。因此,查询可能如下所示 从employee\u表中选择emp\u id、emp\u name 从customer\u表中选择cust\u id、cust\u name、cust\u age 从地址表中选
从employee_表中选择emp_id、emp_name
我有一个行映射器类,它将resultSet中的值映射到employee POJO
我的要求是
查询将由用户输入。因此,查询可能如下所示
从employee\u表中选择emp\u id、emp\u name
从customer\u表中选择cust\u id、cust\u name、cust\u age
从地址表中选择门号、街道名称、位置名称、城市
类似查询
谢谢你抽出时间。示例代码将不胜感激 要回答您的问题:
Map
RowMapper
概念是否有效?如果使用Map
,则可以使用列名作为键,列值作为值。您应该能够创建一个行映射器
实现来实现这一点行映射器的东西
-有,但它是专为POJO设计的,因此您需要为此创建自己的行映射器如果您有需要映射到的对象… 考虑使用
RowMapper
的自定义实现对SQL进行别名,以匹配对象字段名,该实现实际上扩展了beanwrapperfiedsetmapper
因此,如果您的POJO看起来像这样:
public class Employee {
private String employeeId;
private String employeeName;
...
// getters and setters
}
SELECT emp_id employeeId, emp_name employeeName from employee_table
import org.springframework.jdbc.core.RowMapper
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper
public class BeanWrapperRowMapper<T> extends BeanWrapperFieldSetMapper<T> implements RowMapper<T> {
@Override
public T mapRow(final ResultSet rs, final int rowNum) throws SQLException {
final FieldSet fs = getFieldSet(rs);
try {
return super.mapFieldSet(fs);
} catch (final BindException e) {
throw new IllegalArgumentException("Could not bind bean to FieldSet", e);
}
}
private FieldSet getFieldSet(final ResultSet rs) throws SQLException {
final ResultSetMetaData metaData = rs.getMetaData();
final int columnCount = metaData.getColumnCount();
final List<String> tokens = new ArrayList<>();
final List<String> names = new ArrayList<>();
for (int i = 1; i <= columnCount; i++) {
tokens.add(rs.getString(i));
names.add(metaData.getColumnName(i));
}
return new DefaultFieldSet(tokens.toArray(new String[0]), names.toArray(new String[0]));
}
}
然后,您的SQL可以如下所示:
public class Employee {
private String employeeId;
private String employeeName;
...
// getters and setters
}
SELECT emp_id employeeId, emp_name employeeName from employee_table
import org.springframework.jdbc.core.RowMapper
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper
public class BeanWrapperRowMapper<T> extends BeanWrapperFieldSetMapper<T> implements RowMapper<T> {
@Override
public T mapRow(final ResultSet rs, final int rowNum) throws SQLException {
final FieldSet fs = getFieldSet(rs);
try {
return super.mapFieldSet(fs);
} catch (final BindException e) {
throw new IllegalArgumentException("Could not bind bean to FieldSet", e);
}
}
private FieldSet getFieldSet(final ResultSet rs) throws SQLException {
final ResultSetMetaData metaData = rs.getMetaData();
final int columnCount = metaData.getColumnCount();
final List<String> tokens = new ArrayList<>();
final List<String> names = new ArrayList<>();
for (int i = 1; i <= columnCount; i++) {
tokens.add(rs.getString(i));
names.add(metaData.getColumnName(i));
}
return new DefaultFieldSet(tokens.toArray(new String[0]), names.toArray(new String[0]));
}
}
然后,包装好的行映射器将如下所示:
public class Employee {
private String employeeId;
private String employeeName;
...
// getters and setters
}
SELECT emp_id employeeId, emp_name employeeName from employee_table
import org.springframework.jdbc.core.RowMapper
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper
public class BeanWrapperRowMapper<T> extends BeanWrapperFieldSetMapper<T> implements RowMapper<T> {
@Override
public T mapRow(final ResultSet rs, final int rowNum) throws SQLException {
final FieldSet fs = getFieldSet(rs);
try {
return super.mapFieldSet(fs);
} catch (final BindException e) {
throw new IllegalArgumentException("Could not bind bean to FieldSet", e);
}
}
private FieldSet getFieldSet(final ResultSet rs) throws SQLException {
final ResultSetMetaData metaData = rs.getMetaData();
final int columnCount = metaData.getColumnCount();
final List<String> tokens = new ArrayList<>();
final List<String> names = new ArrayList<>();
for (int i = 1; i <= columnCount; i++) {
tokens.add(rs.getString(i));
names.add(metaData.getColumnName(i));
}
return new DefaultFieldSet(tokens.toArray(new String[0]), names.toArray(new String[0]));
}
}
然后您的ItemSqlParameterSourceProvider
实现可能如下所示:
public class MapItemSqlParameterSourceProvider implements
ItemSqlParameterSourceProvider<Map<String, Object>> {
public SqlParameterSource createSqlParameterSource(Map<String, Object> item) {
return new MapSqlParameterSource(item);
}
}
公共类MapItemSqlParameterSourceProvider实现
ItemSqlParameterSourceProvider{
公共SqlParameterSource createSqlParameterSource(映射项){
返回新的MapSqlParameterSource(项);
}
}
我使用Spring的ColumnMapRowMapper找到了问题的解决方案。请从xml配置文件中查找代码段。我没有生成任何POJO类。我用一张地图进行管理,并将其插入ES。映射的键名称应与索引中的字段名称匹配
<step id="slave" xmlns="http://www.springframework.org/schema/batch">
<tasklet>
<chunk reader="pagingItemReader" writer="elasticSearcItemWriter"
processor="itemProcessor" commit-interval="10" />
</tasklet>
</step>
<bean id="pagingItemReader"
class="org.springframework.batch.item.database.JdbcPagingItemReader"
scope="step">
<property name="dataSource" ref="dataSource" />
<property name="queryProvider">
<bean
class="org.springframework.batch.item.database.support.SqlPagingQueryProviderFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="selectClause" value="*******" />
<property name="fromClause" value="*******" />
<property name="whereClause" value="*******" />
<property name="sortKey" value="*******" />
</bean>
</property>
<!-- Inject via the ExecutionContext in rangePartitioner -->
<property name="parameterValues">
<map>
<entry key="fromId" value="#{stepExecutionContext[fromId]}" />
<entry key="toId" value="#{stepExecutionContext[toId]}" />
</map>
</property>
<property name="pageSize" value="10" />
<property name="rowMapper">
<bean class="org.springframework.jdbc.core.ColumnMapRowMapper" />
</property>
</bean>
在我的elasticSearcItemWriter课程中
public class ElasticSearchItemWriter<T> extends AbstractItemStreamItemWriter<T>
implements ResourceAwareItemWriterItemStream<T>, InitializingBean {
....
....
....
@Override
public void write(List<? extends T> items) throws Exception {
client = jestClient.getJestClient();
if (items.size() > 0) {
for (Object item : items) {
@SuppressWarnings("unchecked")
Map<String, Object> map = (Map<String, Object>) item;
// Asynch index
Index index = new Index.Builder(map).index(Start.prop.getProperty(Constants.ES_INDEX_NAME))
.type(Start.prop.getProperty(Constants.ES_INDEX_TYPE)).build();
client.executeAsync(index, new JestResultHandler<JestResult>() {
public void failed(Exception ex) {
}
public void completed(JestResult result) {
}
});
}
}
}
.....
....
}
公共类ElasticSearchItemWriter扩展了AbstractItemStreamItemWriter
实现ResourceAwareItemWriterItemStream,初始化Bean{
....
....
....
@凌驾
public void write(List你可以像下面这样做
SettingsDto settings = SettingsDao.getById(1, new BeanPropertyRowMapper<>(SettingsDto.class));
我的刀法如下
SettingsDto getById(int id, final RowMapper<OMoneySettingsDto> mapper);
您可以在这里使用ORM,将查询作为本机查询运行,以获取JPA entitiesHi Michael。感谢您的回答。您能回答第二点吗?我不太明白使用映射将如何解决我的用例。一些代码片段将非常有帮助。感谢您的时间。我相信他指的是ColumnMapRowMapper
。更多信息在我上面的回答中是这样的,但是列名(或别名)将是键,值将是返回映射中的值。这非常有用。谢谢。)@Dean Clark非常喜欢这个实现,并感谢您提供它。我正在尝试查找BeanWrapperFieldSetMapper的导入。您能提供吗?提前感谢!@Nelda.techspires-已添加到上面!