版权声明： https://blog.csdn.net/ph3636/article/details/83098638
9. 执行StandardRoutingEngine#route获取路由结果，获取分表规则以及分库分表对应的字段列，获取分库分表对应的字段对应的具体值，
public RoutingResult route() {
TableRule tableRule = shardingRule.getTableRule(logicTableName);
Collection<String> databaseShardingColumns = shardingRule.getDatabaseShardingStrategy(tableRule).getShardingColumns();
Collection<String> tableShardingColumns = shardingRule.getTableShardingStrategy(tableRule).getShardingColumns();
Collection<DataNode> routedDataNodes = new LinkedHashSet<>();
if (HintManagerHolder.isUseShardingHint()) {
List<ShardingValue> databaseShardingValues = getDatabaseShardingValuesFromHint(databaseShardingColumns);
List<ShardingValue> tableShardingValues = getTableShardingValuesFromHint(tableShardingColumns);
Collection<DataNode> dataNodes = route(tableRule, databaseShardingValues, tableShardingValues);
for (ShardingCondition each : shardingConditions.getShardingConditions()) {
if (each instanceof InsertShardingCondition) {
((InsertShardingCondition) each).getDataNodes().addAll(dataNodes);
}
}
routedDataNodes.addAll(dataNodes);
} else {
if (shardingConditions.getShardingConditions().isEmpty()) {
routedDataNodes.addAll(route(tableRule, Collections.<ShardingValue>emptyList(), Collections.<ShardingValue>emptyList()));
} else {
for (ShardingCondition each : shardingConditions.getShardingConditions()) {
List<ShardingValue> databaseShardingValues = getShardingValues(databaseShardingColumns, each);
List<ShardingValue> tableShardingValues = getShardingValues(tableShardingColumns, each);
Collection<DataNode> dataNodes = route(tableRule, databaseShardingValues, tableShardingValues);
routedDataNodes.addAll(dataNodes);
if (each instanceof InsertShardingCondition) {
((InsertShardingCondition) each).getDataNodes().addAll(dataNodes);
}
}
}
}
return generateRoutingResult(routedDataNodes);
}路由到对应的数据节点，获取到实际存在的数据库源和表名，再根据xml文件中配置的策略进行选择StandardShardingStrategy#doSharding，PreciseShardingAlgorithm#doSharding选择符合条件的数据节点。
private Collection<DataNode> route(final TableRule tableRule, final List<ShardingValue> databaseShardingValues, final List<ShardingValue> tableShardingValues) {
Collection<String> routedDataSources = routeDataSources(tableRule, databaseShardingValues);
Collection<DataNode> result = new LinkedList<>();
for (String each : routedDataSources) {
result.addAll(routeTables(tableRule, each, tableShardingValues));
}
return result;
}生成最后的路由结果，保存对应的数据库原，保存逻辑表名和实际表名的对应关系。
10. 创建sql语句重写引擎SQLRewriteEngine，重写表名appendTablePlaceholder(result, (TableToken) each, count, sqlTokens);重写()字段列值appendInsertValuesToken(result, (InsertValuesToken) each, count, sqlTokens);
public SQLBuilder rewrite(final boolean isRewriteLimit) {
SQLBuilder result = new SQLBuilder(parameters);
if (sqlTokens.isEmpty()) {
result.appendLiterals(originalSQL);
return result;
}
int count = 0;
sortByBeginPosition();
for (SQLToken each : sqlTokens) {
if (0 == count) {
result.appendLiterals(originalSQL.substring(0, each.getBeginPosition()));
}
if (each instanceof TableToken) {
appendTablePlaceholder(result, (TableToken) each, count, sqlTokens);
} else if (each instanceof SchemaToken) {
appendSchemaPlaceholder(result, (SchemaToken) each, count, sqlTokens);
} else if (each instanceof IndexToken) {
appendIndexPlaceholder(result, (IndexToken) each, count, sqlTokens);
} else if (each instanceof ItemsToken) {
appendItemsToken(result, (ItemsToken) each, count, sqlTokens);
} else if (each instanceof InsertValuesToken) {
appendInsertValuesToken(result, (InsertValuesToken) each, count, sqlTokens);
} else if (each instanceof RowCountToken) {
appendLimitRowCount(result, (RowCountToken) each, count, sqlTokens, isRewriteLimit);
} else if (each instanceof OffsetToken) {
appendLimitOffsetToken(result, (OffsetToken) each, count, sqlTokens, isRewriteLimit);
} else if (each instanceof OrderByToken) {
appendOrderByToken(result, count, sqlTokens);
} else if (each instanceof InsertColumnToken) {
appendSymbolToken(result, (InsertColumnToken) each, count, sqlTokens);
}
count++;
}
return result;
}用SQLRewriteEngine#generateSQL组合成真正的sql语句，获取逻辑实际表的对应关系，以及绑定表的关系。用SQLBuilder拼接sql，不属于占位符的直接拼接，根据逻辑表名获取实际表名，拼接表名以及字段名，解析()参数值以及具体参数值，组合成SQLUnit返回，最后把数据源以及sql语句和具体的参数值包装成SQLExecutionUnit放进SQLRouteResult返回。
public SQLUnit toSQL(final TableUnit tableUnit, final Map<String, String> logicAndActualTableMap, final ShardingRule shardingRule) {
List<Object> insertParameters = new LinkedList<>();
StringBuilder result = new StringBuilder();
for (Object each : segments) {
if (!(each instanceof ShardingPlaceholder)) {
result.append(each);
continue;
}
String logicTableName = ((ShardingPlaceholder) each).getLogicTableName();
String actualTableName = logicAndActualTableMap.get(logicTableName);
if (each instanceof TablePlaceholder) {
result.append(null == actualTableName ? logicTableName : actualTableName);
} else if (each instanceof SchemaPlaceholder) {
SchemaPlaceholder schemaPlaceholder = (SchemaPlaceholder) each;
Optional<TableRule> tableRule = shardingRule.tryFindTableRuleByActualTable(actualTableName);
if (!tableRule.isPresent() && Strings.isNullOrEmpty(shardingRule.getShardingDataSourceNames().getDefaultDataSourceName())) {
throw new ShardingException("Cannot found schema name '%s' in sharding rule.", schemaPlaceholder.getLogicSchemaName());
}
// TODO 目前只能找到真实数据源名称. 未来需要在初始化sharding rule时创建connection,并验证连接是否正确,并获取出真实的schema的名字, 然后在这里替换actualDataSourceName为actualSchemaName
// TODO 目前actualDataSourceName必须actualSchemaName一样,才能保证替换schema的场景不出错, 如: show columns xxx
Preconditions.checkState(tableRule.isPresent());
result.append(tableRule.get().getActualDatasourceNames().iterator().next());
} else if (each instanceof IndexPlaceholder) {
IndexPlaceholder indexPlaceholder = (IndexPlaceholder) each;
result.append(indexPlaceholder.getLogicIndexName());
if (!Strings.isNullOrEmpty(actualTableName)) {
result.append("_");
result.append(actualTableName);
}
} else if (each instanceof InsertValuesPlaceholder) {
InsertValuesPlaceholder insertValuesPlaceholder = (InsertValuesPlaceholder) each;
List<String> expressions = new LinkedList<>();
for (ShardingCondition shardingCondition : insertValuesPlaceholder.getShardingConditions().getShardingConditions()) {
processInsertShardingCondition(tableUnit, (InsertShardingCondition) shardingCondition, expressions, insertParameters);
}
int count = 0;
for (String s : expressions) {
if (0 != count) {
result.append(", ");
}
result.append(s);
count++;
}
} else {
result.append(each);
}
}
if (insertParameters.isEmpty()) {
return new SQLUnit(result.toString(), new ArrayList<>(Collections.singleton(parameters)));
} else {
return new SQLUnit(result.toString(), new ArrayList<>(Collections.singleton(insertParameters)));
}
}11. 继续回到ShardingPreparedStatement#route，根据数据源获取数据库连接AbstractConnectionAdapter#getConnection，放进连接缓存中cachedConnections.put(dataSourceName, result);，执行钩子方法等WrapperAdapter#replayMethodsInvocation，获取PreparedStatement并保存
for (SQLExecutionUnit each : routeResult.getExecutionUnits()) {
PreparedStatement preparedStatement = generatePreparedStatement(each);
routedStatements.add(preparedStatement);
replaySetParameter(preparedStatement, each.getSqlUnit().getParameterSets().get(0));
result.add(new PreparedStatementUnit(each, preparedStatement));
}
private PreparedStatement generatePreparedStatement(final SQLExecutionUnit sqlExecutionUnit) throws SQLException {
Connection connection = getConnection().getConnection(sqlExecutionUnit.getDataSource());
return returnGeneratedKeys ? connection.prepareStatement(sqlExecutionUnit.getSqlUnit().getSql(), Statement.RETURN_GENERATED_KEYS)
: connection.prepareStatement(sqlExecutionUnit.getSqlUnit().getSql(), resultSetType, resultSetConcurrency, resultSetHoldability);
}使用反射方式构造设置参数的方法SetParameterMethodInvocation，执行对应的设置参数的方法invoke，把具体的参数值设置到preparedStatement中，最后返回PreparedStatementUnit。
private void recordSetParameter(final String methodName, final Class[] argumentTypes, final Object... arguments) {
try {
setParameterMethodInvocations.add(new SetParameterMethodInvocation(PreparedStatement.class.getMethod(methodName, argumentTypes), arguments, arguments[1]));
} catch (final NoSuchMethodException ex) {
throw new ShardingException(ex);
}
}
protected void replaySetParameter(final PreparedStatement preparedStatement, final List<Object> parameters) {
setParameterMethodInvocations.clear();
addParameters(parameters);
for (SetParameterMethodInvocation each : setParameterMethodInvocations) {
each.invoke(preparedStatement);
}
}
private void addParameters(final List<Object> parameters) {
for (int i = 0; i < parameters.size(); i++) {
recordSetParameter("setObject", new Class[]{int.class, Object.class}, i + 1, parameters.get(i));
}
}12. 把preparedStatement放入线程池中开始执行，执行结果后清理一些本次缓存的数据，批量信息，参数信息等等以及另外一些收尾工作。
public boolean execute() throws SQLException {
try {
Collection<PreparedStatementUnit> preparedStatementUnits = route();
return new PreparedStatementExecutor(
getConnection().getShardingContext().getExecutorEngine(), routeResult.getSqlStatement().getType(), preparedStatementUnits).execute();
} finally {
JDBCShardingRefreshHandler.build(routeResult, connection).execute();
clearBatch();
}
}
public boolean execute() throws SQLException {
List<Boolean> result = executorEngine.execute(sqlType, preparedStatementUnits, new ExecuteCallback<Boolean>() {
@Override
public Boolean execute(final BaseStatementUnit baseStatementUnit) throws Exception {
return ((PreparedStatement) baseStatementUnit.getStatement()).execute();
}
});
if (null == result || result.isEmpty() || null == result.get(0)) {
return false;
}
return result.get(0);
}ExecutorEngine#execute，取出第一个执行单元同步执行，然后异步执行其他的执行单元，最后把所有的结果包装成ListenableFuture返回，至此，insert语句就解析完毕了。
public <T> List<T> execute(
final SQLType sqlType, final Collection<? extends BaseStatementUnit> baseStatementUnits, final ExecuteCallback<T> executeCallback) throws SQLException {
if (baseStatementUnits.isEmpty()) {
return Collections.emptyList();
}
OverallExecutionEvent event = new OverallExecutionEvent(sqlType, baseStatementUnits.size());
EventBusInstance.getInstance().post(event);
Iterator<? extends BaseStatementUnit> iterator = baseStatementUnits.iterator();
BaseStatementUnit firstInput = iterator.next();
ListenableFuture<List<T>> restFutures = asyncExecute(sqlType, Lists.newArrayList(iterator), executeCallback);
T firstOutput;
List<T> restOutputs;
try {
firstOutput = syncExecute(sqlType, firstInput, executeCallback);
restOutputs = restFutures.get();
// CHECKSTYLE:OFF
} catch (final Exception ex) {
// CHECKSTYLE:ON
event.setException(ex);
event.setEventExecutionType(EventExecutionType.EXECUTE_FAILURE);
EventBusInstance.getInstance().post(event);
ExecutorExceptionHandler.handleException(ex);
return null;
}
event.setEventExecutionType(EventExecutionType.EXECUTE_SUCCESS);
EventBusInstance.getInstance().post(event);
List<T> result = Lists.newLinkedList(restOutputs);
result.add(0, firstOutput);
return result;
}
private <T> T executeInternal(final SQLType sqlType, final BaseStatementUnit baseStatementUnit, final ExecuteCallback<T> executeCallback,
final boolean isExceptionThrown, final Map<String, Object> dataMap) throws Exception {
synchronized (baseStatementUnit.getStatement().getConnection()) {
T result;
ExecutorExceptionHandler.setExceptionThrown(isExceptionThrown);
ExecutorDataMap.setDataMap(dataMap);
List<AbstractExecutionEvent> events = new LinkedList<>();
for (List<Object> each : baseStatementUnit.getSqlExecutionUnit().getSqlUnit().getParameterSets()) {
events.add(getExecutionEvent(sqlType, baseStatementUnit, each));
}
for (AbstractExecutionEvent event : events) {
EventBusInstance.getInstance().post(event);
}
try {
result = executeCallback.execute(baseStatementUnit);
} catch (final SQLException ex) {
for (AbstractExecutionEvent each : events) {
each.setEventExecutionType(EventExecutionType.EXECUTE_FAILURE);
each.setException(ex);
EventBusInstance.getInstance().post(each);
ExecutorExceptionHandler.handleException(ex);
}
return null;
}
for (AbstractExecutionEvent each : events) {
each.setEventExecutionType(EventExecutionType.EXECUTE_SUCCESS);
EventBusInstance.getInstance().post(each);
}
return result;
}
}
private AbstractExecutionEvent getExecutionEvent(final SQLType sqlType, final BaseStatementUnit baseStatementUnit, final List<Object> parameters) {
AbstractExecutionEvent result;
if (SQLType.DQL == sqlType) {
result = new DQLExecutionEvent(baseStatementUnit.getSqlExecutionUnit().getDataSource(), baseStatementUnit.getSqlExecutionUnit().getSqlUnit(), parameters);
} else {
result = new DMLExecutionEvent(baseStatementUnit.getSqlExecutionUnit().getDataSource(), baseStatementUnit.getSqlExecutionUnit().getSqlUnit(), parameters);
}
return result;
}