源码剖析-揭秘如何设置的参数?
# 入口：PreparedStatementHandler#parameterize方法
设置PreparedStatement的参数
@Override
public void parameterize(Statement statement) throws SQLException {
// 通过ParameterHandler处理参数
parameterHandler.setParameters((PreparedStatement) statement);
}
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# DefaultParameterHandler#setParameters
设置参数
@Override
public void setParameters(PreparedStatement ps) {
ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());
// 获取要设置的参数映射信息
List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
if (parameterMappings != null) {
for (int i = 0; i < parameterMappings.size(); i++) {
ParameterMapping parameterMapping = parameterMappings.get(i);
// 只处理入参
if (parameterMapping.getMode() != ParameterMode.OUT) {
Object value;
// 获取属性名称
String propertyName = parameterMapping.getProperty();
if (boundSql.hasAdditionalParameter(propertyName)) { // issue #448 ask first for additional params
value = boundSql.getAdditionalParameter(propertyName);
} else if (parameterObject == null) {
value = null;
} else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
value = parameterObject;
} else {
MetaObject metaObject = configuration.newMetaObject(parameterObject);
value = metaObject.getValue(propertyName);
}
// 获取每个参数的类型处理器，去设置入参和获取返回值
TypeHandler typeHandler = parameterMapping.getTypeHandler();
// 获取每个参数的JdbcType
JdbcType jdbcType = parameterMapping.getJdbcType();
if (value == null && jdbcType == null) {
jdbcType = configuration.getJdbcTypeForNull();
}
try {
// 给PreparedStatement设置参数
typeHandler.setParameter(ps, i + 1, value, jdbcType);
} catch (TypeException e) {
throw new TypeException(
"Could not set parameters for mapping: " + parameterMapping + ". Cause: " + e, e);
} catch (SQLException e) {
throw new TypeException(
"Could not set parameters for mapping: " + parameterMapping + ". Cause: " + e, e);
}
}
}
}
}
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# BaseTypeHandler#setParameter
给PreparedStatement设置参数
@Override
public void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
if (parameter == null) {
if (jdbcType == null) {
throw new TypeException(
"JDBC requires that the JdbcType must be specified for all nullable parameters.");
}
try {
ps.setNull(i, jdbcType.TYPE_CODE);
} catch (SQLException e) {
throw new TypeException("Error setting null for parameter #" + i + " with JdbcType " + jdbcType + " . "
+ "Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. "
+ "Cause: " + e, e);
}
} else {
try {
// 通过PreparedStatement的API去设置非空参数
setNonNullParameter(ps, i, parameter, jdbcType);
} catch (Exception e) {
throw new TypeException("Error setting non null for parameter #" + i + " with JdbcType " + jdbcType
+ " . "
+ "Try setting a different JdbcType for this parameter or a different configuration property. "
+ "Cause: " + e, e);
}
}
}
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# xxxTypeHandler#setNonNullParameter
通过PreparedStatement的API去设置非空参数 例如：ArrayTypeHandler
@Override
public void setNonNullParameter(PreparedStatement ps, int i, Object parameter, JdbcType jdbcType) throws SQLException {
ps.setArray(i, (Array) parameter);
}
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上次更新: 2025/04/03, 11:07:08
