xml中某些特殊符號作為內容資訊時需要做轉義,否則會對檔案的合法性和使用造成影響

Html程式碼

1. &lt; <
2. &gt; >
3. &amp; &
4. &apos; '
5. &quot; "

&lt; < 
&gt; > 
&amp; & 
&apos; ' 
&quot; "

在mapper檔案中寫sql語句時,為避免不必要的麻煩(如<等),建議使用<![CDATA[ ]]>來標記不應由xml解析器進行解析的文字資料,由<![CDATA[ ]]>包裹的所有的內容都會被解析器忽略 <![CDATA[ sql語句 ]]>

Xml程式碼

1. <select id="getAccountsByBranch" resultType="Account" parameterType="string">
2. <![CDATA[SELECT * FROM t_acctreg_accounts where acctno < #{acctno}]]>
3. </select>

<select id="getAccountsByBranch" resultType="Account" parameterType="string">
	<![CDATA[SELECT * FROM t_acctreg_accounts where acctno < #{acctno}]]>
</select>

將整個sql語句用<![CDATA[ ]]>標記來避免衝突，在一般情況下都是可行的,但是如果這樣寫

Xml程式碼

1. <select id="getAccountErrorCount" resultType="int" parameterType="map">
2. <![CDATA[
3. select count(*) from t_acctreg_accounterror
4. <where>
5. <if test="enddate != null and enddate != ''">
6. createdate <= #{enddate}
7. </if>
8. <if test="acctno != null and acctno != ''">
9. AND acctno LIKE '%'||#{acctno}||'%'
10. </if>
11. </where>
12. ]]>
13. </select>

<select id="getAccountErrorCount" resultType="int" parameterType="map">
	<![CDATA[
	select count(*) from t_acctreg_accounterror
	<where>
		<if test="enddate != null and enddate != ''">
			createdate <= #{enddate}
		</if>
		<if test="acctno != null and acctno != ''">
			AND acctno LIKE '%'||#{acctno}||'%'
		</if>
	</where>
	]]>
</select>

就會收到錯誤資訊:

org.springframework.jdbc.UncategorizedSQLException: Error setting null parameter. Most JDBC drivers require that the JdbcType must be specified for all nullable parameters. Cause: java.sql.SQLException: 無效的列型別: 1111 ; uncategorized SQLException for SQL []; SQL state [99999]; error code [17004]; 無效的列型別: 1111; nested exception is java.sql.SQLException: 無效的列型別: 1111

這是由於該sql配置中有動態語句(where,if),where,if 條件不能放在<![CDATA[ ]]>中,否則將導致無法識別動態判斷部分,導致整個sql語句非法.應該縮小範圍，只對有字元衝突部分進行合法性調整

Xml程式碼

1. <select id="getAccountErrorCount" resultType="int" parameterType="map">
2. select count(*) from t_acctreg_accounterror
3. <where>
4. <if test="enddate != null and enddate != ''">
5. <![CDATA[createdate <= #{enddate}]]>
6. </if>
7. <if test="acctno != null and acctno != ''">
8. <![CDATA[AND acctno LIKE '%'||#{acctno}||'%']]>
9. </if>
10. </where>
11. </select>

<select id="getAccountErrorCount" resultType="int" parameterType="map">
	select count(*) from t_acctreg_accounterror
	<where>
		<if test="enddate != null and enddate != ''">
			<![CDATA[createdate <= #{enddate}]]>
		</if>
		<if test="acctno != null and acctno != ''">
			<![CDATA[AND acctno LIKE '%'||#{acctno}||'%']]>
		</if>
	</where>
</select>

還有在向oracle插入資料時，mybatis3報Error setting null parameter. Most JDBC drivers require that the JdbcType must be specified for all nullable parameters，是由於引數出現了null值,對於Mybatis,如果進行操作的時候,沒有指定jdbcType型別的引數,mybatis預設jdbcType.OTHER導致,給引數加上jdbcType可解決(注意大小寫)

http://code.google.com/p/mybatis/issues/detail?id=224&q=Error%20setting%20null%20parameter&colspec=ID

Xml程式碼

1. <insert id="insertAccountError" statementType="PREPARED"
2. parameterType="AccountError">
3. INSERT INTO t_acctreg_accounterror(createdate,acctno, errorinfo)
4. VALUES(#{createdate,jdbcType=DATE},#{acctno,jdbcType=VARCHAR},#{errorinfo,jdbcType=VARCHAR})
5. </insert>