http断点续传简单实现（java)

/* 4$, W\d  
**SiteFileFetch.java D^>d<LX  
*/ Fs~*-R$  
package NetFox; x>mI$K(6M  
import java.io.*; wQhuU  
import java.net.*; 8mmnnf{P  
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public class SiteFileFetch extends Thread { UAz^P6iQ`~  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ?7)v:$
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long[] nStartPos; //开始位置 4~A$u^scn  
long[] nEndPos; //结束位置 "oiN8#Hf  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 _vb'3~'S  
long nFileLength; //文件长度 )c*xKij  
boolean bFirst = true; //是否第一次取文件 qT$IV\;_  
boolean bStop = false; //停止标志 GK-P6d  
File tmpFile; //文件下载的临时信息 hC8WRxEGq  
DataOutputStream output; //输出到文件的输出流 Z'9|
 

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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） #%ld~dgz-  
public SiteFileFetch(SiteInfoBean bean) throws IOException C7R3W,  
{ K"t?  
siteInfoBean = bean; NAtDt=  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); 6wu`;>  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); >`&2]Wc)  
if(tmpFile.exists ()) dZIbajs'  
{ r?Mf3U^G  
bFirst = false; :4
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read_nPos(); ks phO-  
} OA6i/3 #8  
else t}I@Rmso  
{ fsK=]~<g  
nStartPos = new long[bean.getNSplitter()]; {5  pK8  
nEndPos = new long[bean.getNSplitter()]; @",
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} tA4Ra,-c  
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} UkD\ma  
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public void run() /N%i6t<xU  
{ 3O4lGe#u  
//获得文件长度 V;RgO}  
//分割文件 ;p~!('{P  
//实例FileSplitterFetch MYb^G\K  
//启动FileSplitterFetch线程 T#!% Uzz  
//等待子线程返回 U5-8It2OR  
try{ "|J6*s   
if(bFirst) 4yqYs>  
{ "3]}V=L<5  
nFileLength = getFileSize(); \ ;]{`  
if(nFileLength == -1) e(^I.`9z  
{ MC,Qv9m  
System.err.println("File Length is not known!"); oDD"h,Z  
} !hfpa_5  
else if(nFileLength == -2) EUI*:JU-  
{ :+>7m  
System.err.println("File is not access!"); ;*zLf 9i  
} 5*A5Y E-  
else Q3=5q w^  
{ y2?9pVLa\y  
for(int i=0;i<nStartPos.length;i++) PHT<]:"`<  
{ 'l!\2Wv2  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); l,Y5VGiH#  
} Oprfp^L  
for(int i=0;i<nEndPos.length-1;i++) *szs"mQ/  
{ I:oEt  
nEndPos = nStartPos[i+1]; Ebj0 {ZL  
} w[l#0ZZ  
nEndPos[nEndPos.length-1] = nFileLength; d>I)_05t  
} #E=8kbD7  
} V D7^wd9  
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GK,{$SC+=  
//启动子线程 t
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; t@#5 G* _Q  
for(int i=0;i<nStartPos.length;i++) (i(E~^O  
{ EI?8/c  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), vvY?8/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ,KM%/;1Dm  
nStartPos,nEndPos,i); ` W);+s  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); OMmfTlM%  
fileSplitterFetch.start(); /@ g 8MUq7  
} eJ<P  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 6rmx{Bt  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); z<!A;.iD  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", "v wLj:  
nEndPos = " + nFileLength); $ eL-fg  
// fileSplitterFetch[nPos.length-1].start(); 1TA!9cz0Z  
]<YS7.pT  
q Sv!5&u  
//等待子线程结束 r9bAbE bI  
//int count = 0; C_ d|2C6  
//是否结束while循环 aw lq/
 
boolean breakWhile = false; (>u1O V  
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while(!bStop) C^'r>0  
{ "WGKwi=W  
write_nPos(); la)+"uW  
Utility.sleep(500); dn])6Xl;i  
breakWhile = true; [3S17tTc3  
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for(int i=0;i<nStartPos.length;i++) 5M'cOJ  
{ [bo"!Qk%  
if(!fileSplitterFetch.bDownOver) iKu3'jZ/O  
{ cy mC?8<  
breakWhile = false; .Xf_U.h$*@  
break; "8zMe L  
} *UW 8|\;  
} BH^*K/^  
if(breakWhile) #k>n5cR@0  
break; 0)h.[O8@>  
ZW"f*vwQo  

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//count++; ?Q=(?yR0]  
//if(count>4) /{8Y,pZbu  
// siteStop(); @##}zku  
} H*0g*(  
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#WG;p(?:  
System.err.println("文件下载结束！"); 3K~^H1l  
} D1>*ml  
catch(Exception e){e.printStackTrace ();} @|ZUyat  
} 7u^wO<  
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~MB)}!S:  
//获得文件长度 $X.F=Kv
 
public long getFileSize() ?XyrG1('  
{ %j17QD8  
int nFileLength = -1; |SMigSu r`  
try{ !U(S?:hvW  
URL url = new URL(siteInfoBean.getSSiteURL()); hV`?, ~K  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); r/N
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httpConnection.setRequestProperty("User-Agent","NetFox"); *1b0IQ$g  
;XZN0A2  
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int responseCode=httpConnection.getResponseCode(); Q2)5A&U\  
if(responseCode>=400) XZ$g~r  
{ 6OC4?#96%'  
processErrorCode(responseCode); sP@XV/`3L6  
return -2; //-2 represent access is error mGP%"R2X  
} }mZCQJ#`  
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String sHeader; MMaS  
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for(int i=1;;i++) RmKbnS$*q  
{ Z9% u,Cb  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Pk5\v0vkg  
//Utility.log(in.readLine()); :Zq?V`+M  
sHeader=httpConnection.getHeaderFieldKey(i); JDnW
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if(sHeader!=null) L!/{Z  
{ 9,Dw;|A]  
if(sHeader.equals("Content-Length")) 0VR,I{<.{  
{ u|ih
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 32J/   
break; Fgwe`[  
} 9_&]7ABV  
} \KpJIHkBRy  
else 4TU\SP8sM  
break; vft7-|8T  
} &];W#9"Z  
} [!KsAsmk  
catch(IOException e){e.printStackTrace ();} *}(
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catch(Exception e){e.printStackTrace ();} r_'];  
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Utility.log(nFileLength); TDPQ+Kg_  
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return nFileLength; k-s|gC4  
} cqZ
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//保存下载信息（文件指针位置） *$('ous8  
private void write_nPos() yswf2F  
{ V*%><r  
try{ <7ag=IgDy  
output = new DataOutputStream(new FileOutputStream(tmpFile)); NgxJz ]b  
output.writeInt(nStartPos.length); ) AGE"M3X  
for(int i=0;i<nStartPos.length;i++) HPO:aGU  
{ tg/!=g  
// output.writeLong(nPos); 4 l+z  
output.writeLong(fileSplitterFetch.nStartPos); Lq@uwiq!  
output.writeLong(fileSplitterFetch.nEndPos); ]wbV1Y"
 
} 3<a|_(K  
output.close(); nM8'="$  
} 6(A"5B=\  
catch(IOException e){e.printStackTrace ();} m5
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catch(Exception e){e.printStackTrace ();} pwVGe|h%,  
} 
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//读取保存的下载信息（文件指针位置） kO
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private void read_nPos() YB{'L +Wbw  
{ \Q?#^<O  
try{ *'n=LB8R  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); BH$hd|KD<  
int nCount = input.readInt(); URr{J}5  
nStartPos = new long[nCount]; 2'ws@U}lR  
nEndPos = new long[nCount]; J}@.f-W\j  
for(int i=0;i<nStartPos.length;i++) _t X1z^  
{ J6zU#  
nStartPos = input.readLong(); C6tfFS3bq  
nEndPos = input.readLong(); 7.yCs[Z  
} `RE K,^U  
input.close(); q(#,X~0  
} u~N'UD1x  
catch(IOException e){e.printStackTrace ();} #K>Ue>hx  
catch(Exception e){e.printStackTrace ();} \/m-G:|  
} j3 @Q  
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private void processErrorCode(int nErrorCode) !i{5mc\  
{ [RDY(}P%  
System.err.println("Error Code : " + nErrorCode); V)oKsO
 
} '?mky,:HT  
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qs (L2'7/  
//停止文件下载 u@4khN: ^p  
public void siteStop() 0SZ:C(]  
{ 5S7ATr(*  
bStop = true; }qhND-9#@  
for(int i=0;i<nStartPos.length;i++) OR10IS  
fileSplitterFetch.splitterStop(); "@xL9[d  
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} !,DA`Yt  
} ~^g*cA t}  
//负责部分文件的抓取 %W2 o`W$  
**FileSplitterFetch.java S)^eHuXPI  
*/ jyRz53  
package NetFox; 'z};tIOKJk  
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import java.io.*; > mP([]  
import java.net.*; AD'c#CT  
hi ),PfAV  
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public class FileSplitterFetch extends Thread { GkdxwuRw  
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String sURL; //File URL $j0<ef!  
long nStartPos; //File Snippet Start Position 6s:  
long nEndPos; //File Snippet End Position q:,ck@-4  
int nThreadID; //Thread's ID P`n"E8"ab<  
boolean bDownOver = false; //Downing is over 55Ye7P-d  
boolean bStop = false; //Stop identical TI^X gl~  
FileAccessI fileAccessI = null; //File Access interface *Y ?&N2@c  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException )aX#RM? N  
{ @WzrrCpj  
this.sURL = sURL; pm*i!3g'  
this.nStartPos = nStart; S^SF!k=  
this.nEndPos = nEnd; `{n
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nThreadID = id; :
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fileAccessI = new FileAccessI(sName,nStartPos);//定位 Vf$
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} "Qe2U(U
n  
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public void run() v*@R U  
{ kE{-h'xADD  
while(nStartPos < nEndPos && !bStop) K=J">^uW  
{ 3T
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try{ hh^_Z| 5  
URL url = new URL(sURL); l`EKL2n  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); n!?u/[@  
httpConnection.setRequestProperty("User-Agent","NetFox"); aN"dk-eK  
String sProperty = "bytes="+nStartPos+"-"; )m10IyUAY  
httpConnection.setRequestProperty("RANGE",sProperty); 2TX.%%Ze  
Utility.log(sProperty); $&0\BvS  
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InputStream input = httpConnection.getInputStream(); U{0! <*W>  
//logResponseHead(httpConnection); (0S;eM&  
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byte[] b = new byte[1024]; ~"U^N:I"  
int nRead; (=QiXX1r  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) G-R
E  
{ o:RO(oA0?  
nStartPos += fileAccessI.write(b,0,nRead); ]Cc8[ZC  
//if(nThreadID == 1) od]1:8OF  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); x^!LA,`j  
} A}0u-W  
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Utility.log("Thread " + nThreadID + " is over!"); qoJ<e`h}
 
bDownOver = true;  k< g  
//nPos = fileAccessI.write (b,0,nRead); 9*xv ,Yz8  
} -T.C?Q g  
catch(Exception e){e.printStackTrace ();} <Lfo5:.  
}  LhtA]z,m  
} G\H|\i  
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//打印回应的头信息 [kPF Jf  
public void logResponseHead(HttpURLConnection con) kBJx`tjtp  
{ )E=~ _`XO  
for(int i=1;;i++) oJor ]QYK  
{ JA6#qlylL  
String header=con.getHeaderFieldKey(i); t;)`+K#1:  
if(header!=null) ,gn**E  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); "v5jYz5M  
Utility.log(header+" : "+con.getHeaderField(header)); 9rM6kLD  
else 7!#34ue  
break; Y-:dPc{  
} v\Xyz )  
} @"B
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public void splitterStop() "P8cgj C  
{ ]dQ  
bStop = true; -jL10~/  
} [X'u={  
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} eih~ SBSH  
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/* mu&%ph=  
**FileAccess.java N#4"P:Sv  
*//文件访问(定位，写) fk?(mxx"  
package NetFox; !1ZrS  
import java.io.*; B-EDVMu  
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public class FileAccessI implements Serializable{ gjex;h  
1A;f[Rze  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 cR/z;*wr7  
RandomAccessFile oSavedFile; OE_A$8L  
long nPos; ];au! _o  
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*odwg$  
public FileAccessI() throws IOException kU[#. y=%p  
{ v[=TPfX0  
this("",0); {qPu}?0
 
} 9|1J pb  
*WZ?C|6+  
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public FileAccessI(String sName,long nPos) throws IOException s N|7  
{ ($*R>*6<x  
oSavedFile = new RandomAccessFile(sName,"rw"); VW*d*!  
this.nPos = nPos; n~G-X  
oSavedFile.seek(nPos); A&($X)t  
} Qwu~{tf+'  
137:T:  
7q|51rZz  
public synchronized int write(byte[] b,int nStart,int nLen) 8d*W7>rq  
{ Dro2R_j{  
int n = -1; KPMId`kf  
try{ cuo'V*nWQ  
oSavedFile.write(b,nStart,nLen); ":,J<|Oy  
n = nLen; ok<!/"RX$  
} a;[=bp  
catch(IOException e) $jgEB+  
{ )0p7d:%mV  
e.printStackTrace (); FW--|X]8  
} qQx5n  
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*HXx;:  
return n; x*2I]4  
} k1Thjt  
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} S 0L"5B@  
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/* i2(lqhaP  
**SiteInfoBean.java l!YjDm{E  
*/ $g+q;Y~i0  
package NetFox; ;Vh5nO  
3X A8\Mg  
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public class SiteInfoBean { Y<EdFzle  
76rRF   
W2G@-`,  
private String sSiteURL; //Site's URL B gB]M3Il  
private String sFilePath; //Saved File's Path z;d]=PT  
private String sFileName; //Saved File's Name h,%b>JFo  
private int nSplitter; //Count of Splited Downloading File r&?i>.Kz8  
{m
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public SiteInfoBean() Xj("  
{//nSplitter的缺省值为5 AEr8^6  
//default value of nSplitter is 5 !$5.\D  
this("","","",5); FF7  
} Ua=w;h  
?RVY%s;g  
6Om)e=gU/  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) t;e+WZkV  
{ T.kQ] h2ZG  
sSiteURL= sURL; oD>j26Q  
sFilePath = sPath; VLO!hA#  
sFileName = sName; +9d]([Lx  
this.nSplitter = nSpiltter; Y] "_}  
|'" 17c&  
@ATJ|5.gr  
} )`B n"=  
[>N`)]fP  
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public String getSSiteURL() _yJAn\  
{ R#0Z  
return sSiteURL; ?YTngIa  
} H^N 5yOj/  
DEcsFC/SK  
a2tRmil  
public void setSSiteURL(String value) :`w'}h7m  
{ lyYi2& %  
sSiteURL = value; }E%#g#  
} /<WK2G  
b ?-VZA:  
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public String getSFilePath() FJl_2  
{ N 2\lBi  
return sFilePath; 8kwe._&)  
} Bw;LGEHi|  
oPP
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C
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public void setSFilePath(String value) X|iWnz+^  
{ V<%eWT)x7C  
sFilePath = value; 9;*-y$@  
} &>]c"?C*  
]gHi5]\NC
 
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public String getSFileName() s v}o%  
{ eAPNF?0yh  
return sFileName; CCQ38P@rv  
} a\BV%'Zqg  
fI([vI
 
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public void setSFileName(String value) GV"HkE;  
{ VX<jg#(  
sFileName = value; '!wI8f  
} t
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2iJ)K rw  
^UEExjf  
public int getNSplitter() |{a`,%mw  
{ "7&DuF$s)  
return nSplitter; 9h$08l  
} jLZ^EM-  
c{X:0man  
lPywrTG0  
public void setNSplitter(int nCount) [m9Iz!E  
{ SZhW)0  
nSplitter = nCount; #2~-I  
} th?w&;L  
}
{#,eD  
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/* 7|/Ct
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**Utility.java $yA>
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*/ Q*J8`J:#^R  
package NetFox; ~5Cid)Q}@o  
&Is}<Ew  
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public class Utility { VoTnm   
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public Utility() 1YrIcovi-  
{ ZVin+z  
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} $gv3Up"U  
7`c\~_Df_  
//线程睡眠 aA|<W g  
public static void sleep(int nSecond) XJ3p<  
{ .a0]1IkatV  
try{ $k,wA8OZ-  
Thread.sleep(nSecond); A./VO  
} Q,f~7IVX  
catch(Exception e) b-+~D9U<  
{ 0S%xm'|N  
e.printStackTrace (); l 7XeZ} S  
} $:i%\7=  
} 1j!LK-  
w I7iE4\vz  
//日志
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public static void log(String sMsg) KS3>c7  
{ \Xr Sn_p-  
System.err.println(sMsg); I+4#LR3;  
} =G9 9U/  
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fVXZfq6  
public static void log(int sMsg) 6` 8H k;  
{ bl8EzO  
System.err.println(sMsg); 0,z3A>C  
} dx&!RK+  
} P"%QFt,  
8nj^x?bn  
`Q@w*ta)  
/* .T63:  
**TestMethod.java 5vmc'Om  
*/ XB.xIApmy  
package NetFox; Nf!g1D"U  
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L2,.af6+  
public class TestMethod { Ki,SFww8r  
3tjF4C>h|  
&qjc+-r{l  
public TestMethod() ,'nd~{pX"(  
{ ///xx/weblogic60b2_win.exe 3bd(.he2u  
try{ jGSY$nt9  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ieL7jN,'m  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); ]VCVV!G_=n  
SiteFileFetch fileFetch = new SiteFileFetch(bean); 9Ev<t\B  
fileFetch.start(); 5Qh$>R4!"  
} VK]cZ%)  
catch(Exception e){e.printStackTrace ();} [B,w\PLub  
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^c-8~r|y,  
} 4m:D8&D_M  
-91*VBrOd  
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public static void main(String[] args) d$H  
{ wwuM!Z+  
new TestMethod(); k Xg&}n7  
} Lhz*o6)  
} sc0.!6^'V  
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